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Discussion Groups | FPGA-CPU | Re: Simple Character CRT Core Needed

This list is for discussion of the design and implementation of field-programmable gate array based processors and integrated systems. It is also for discussion and community support of the XSOC Project (see http://www.fpgacpu.org/xsoc).

Simple Character CRT Core Needed - rtstofer - Aug 30 18:14:00 2004

Does anyone have information on where I might get a free (or very
low cost) CRT core? I am looking for text only, 25 lines of 80
chars. On the surface the design seems simple enough but if it has
already been done there is not much point in doing it again.

I have some space left in my Spartan IIE with the T80 core running
CP/M. I might as well fill it up and drive a VGA monitor instead of
a physical terminal or something like Hyperterminal. I would also
add a keyboard interface.

Thanks!






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Re: Simple Character CRT Core Needed - Arius - Rick Collins - Aug 30 18:38:00 2004

At 07:14 PM 8/30/2004, you wrote:

>Does anyone have information on where I might get a free (or very
>low cost) CRT core? I am looking for text only, 25 lines of 80
>chars. On the surface the design seems simple enough but if it has
>already been done there is not much point in doing it again.
>
>I have some space left in my Spartan IIE with the T80 core running
>CP/M. I might as well fill it up and drive a VGA monitor instead of
>a physical terminal or something like Hyperterminal. I would also
>add a keyboard interface.
>
>Thanks! Try opencores.org, they have a number of cores and one is a video controller.

http://www.opencores.org/projects.cgi/web/vga_lcd

If you only need text, you might be better off designing your own and
saving the logic. An 80x25 text display is very, very simple and should
not take much time to design. If you want, I might do it as an exercise. :)

Be aware that VGA uses ADC converters to drive the three colors. You can
kludge the interface from a digital output like this...

http://www.fpga4fun.com/PongGame.html

This sort of thing can give you up to 8 colors which is plenty for a text
display. You can also add a few more resistors (and outputs) and have
three or four levels on each output which can give you up to 64
colors. Much beyond that and you will likely see problems with quality.
Rick Collins
Arius - A Signal Processing Solutions Company
Specializing in DSP and FPGA design http://www.arius.com
4 King Ave 301-682-7772 Voice
Frederick, MD 21701-3110 301-682-7666 FAX





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Re: Simple Character CRT Core Needed - Lee_Hotmail - Aug 31 1:01:00 2004

Hi All,

It might be worth looking at the www.ExpressIP.co.uk web site as they give
away a free VGA graphics controller that can also work on a TV as well. It
works with our PS2 mouse (or other device) controller.
It has a font rendering engine included.

You also get an SDRAM controller (high performance) DMA engine, risc cpu (16
bit with i / d cache, c- compiler etc), RS232 + other cores

WEB : www.ExpressIP.co.uk

Thanks Lee ----- Original Message -----
From: "rtstofer" <>
To: <>
Sent: Tuesday, August 31, 2004 12:14 AM
Subject: [fpga-cpu] Simple Character CRT Core Needed >
> Does anyone have information on where I might get a free (or very
> low cost) CRT core? I am looking for text only, 25 lines of 80
> chars. On the surface the design seems simple enough but if it has
> already been done there is not much point in doing it again.
>
> I have some space left in my Spartan IIE with the T80 core running
> CP/M. I might as well fill it up and drive a VGA monitor instead of
> a physical terminal or something like Hyperterminal. I would also
> add a keyboard interface.
>
> Thanks! > To post a message, send it to:
> To unsubscribe, send a blank message to:

> Yahoo! Groups Links




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Re: Simple Character CRT Core Needed - John Kent - Aug 31 3:17:00 2004

Hi,

There is a simple 64 x 32 text character display in my System09 SOC.
It should be portable to the T80.
Getting 25 x 80 characters would need a bit more work mapping
the row and column address.

http://members.optushome.com.au/jekent/system09/index.html
(Look at the bottom of the page)

It uses a 25MHz Pixel Clock and makes use of the Block RAM
(if I remember correctly) for the Text buffer, Colour Attribute buffer
and character generator. It supports 4 bits of forground colour and
4 bits of background colour.

It has 4 registers:

Cursor Row Address,
Cursor Colum Address,
Text Character
Colour Attribute.

To Move the cursor you increment the column address
to write a character, you set up the colour Atribute and write an
ASCII character to the Text Character Register.
It's very basic and does not do anything like clearing the bottom
line on line feeds ... you have to do that in software.

It was designed for Tony Burch's FPGA board.

I've also written the open cores P/S 2 keyboard in VHDL.
(It was in Verilog). That's availaible in System09 too.

John. rtstofer wrote:

>Does anyone have information on where I might get a free (or very
>low cost) CRT core? I am looking for text only, 25 lines of 80
>chars. On the surface the design seems simple enough but if it has
>already been done there is not much point in doing it again.
>
>I have some space left in my Spartan IIE with the T80 core running
>CP/M. I might as well fill it up and drive a VGA monitor instead of
>a physical terminal or something like Hyperterminal. I would also
>add a keyboard interface.
>
>Thanks! >
--
http://members.optushome.com.au/jekent




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Re: Simple Character CRT Core Needed - John Kent - Aug 31 3:25:00 2004

I stand corrected,
5 registers. It also has a Row offset register for scrolling the screen

J.

John Kent wrote:

>Cursor Row Address,
>Cursor Colum Address,
>Text Character
>Colour Attribute.
--
http://members.optushome.com.au/jekent



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Re: Simple Character CRT Core Needed - rtstofer - Aug 31 9:23:00 2004


Thanks! I'll give it a look. I am using Tony Burch's board as well.
The ExpressIP site is pretty useful as well. They have a lot of IP
stuff to go with their board.

--- In , John Kent <jekent@o...> wrote:
> Hi,
>
> There is a simple 64 x 32 text character display in my System09
SOC.
> It should be portable to the T80.
> Getting 25 x 80 characters would need a bit more work mapping
> the row and column address.
>
> http://members.optushome.com.au/jekent/system09/index.html
> (Look at the bottom of the page)
>
> It uses a 25MHz Pixel Clock and makes use of the Block RAM
> (if I remember correctly) for the Text buffer, Colour Attribute
buffer
> and character generator. It supports 4 bits of forground colour and
> 4 bits of background colour.
>
> It has 4 registers:
>
> Cursor Row Address,
> Cursor Colum Address,
> Text Character
> Colour Attribute.
>
> To Move the cursor you increment the column address
> to write a character, you set up the colour Atribute and write an
> ASCII character to the Text Character Register.
> It's very basic and does not do anything like clearing the bottom
> line on line feeds ... you have to do that in software.
>
> It was designed for Tony Burch's FPGA board.
>
> I've also written the open cores P/S 2 keyboard in VHDL.
> (It was in Verilog). That's availaible in System09 too.
>
> John. > rtstofer wrote:
>
> >Does anyone have information on where I might get a free (or very
> >low cost) CRT core? I am looking for text only, 25 lines of 80
> >chars. On the surface the design seems simple enough but if it
has
> >already been done there is not much point in doing it again.
> >
> >I have some space left in my Spartan IIE with the T80 core
running
> >CP/M. I might as well fill it up and drive a VGA monitor instead
of
> >a physical terminal or something like Hyperterminal. I would
also
> >add a keyboard interface.
> >
> >Thanks!
> >
> >
> >
> --
> http://members.optushome.com.au/jekent



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Re: Simple Character CRT Core Needed - rtstofer - Aug 31 13:32:00 2004


I had seen the listing at opencores and it seemed far too complex.
At the moment I think I just want 80x25 but it also needs to do the
control codes for a TV950 or ADM3a (switchable?) as some of the old
software is configured and I can't seem to get it to change - Turbo
Pascal and its TINST for example. I don't know why I can't get it
to work but I think it has something to do with an error in the
download. I had a large Fortran program that wouldn't run until I
downloaded the compiler/linker and recompiled on the target.
Curious... Well, I haven't used these programs in 20 years so it's
possible I have forgotten some of the details.

I bought the Xilinx Spartan-3 Starter Kit the other day (what a
bargain for $100) and started to play with it last night. What do
you know? There's a reason for the VGA connector on the board -
there is a text mode VGA component included and it is ready to rock
and roll. There's a ton of stuff that comes with this kit and,
although a little small at 200k gates, $100 is not much tuition
these days.

--- In , Arius - Rick Collins
<dsprelated@a...> wrote:
> At 07:14 PM 8/30/2004, you wrote:
>
> >Does anyone have information on where I might get a free (or very
> >low cost) CRT core? I am looking for text only, 25 lines of 80
> >chars. On the surface the design seems simple enough but if it
has
> >already been done there is not much point in doing it again.
> >
> >I have some space left in my Spartan IIE with the T80 core running
> >CP/M. I might as well fill it up and drive a VGA monitor instead
of
> >a physical terminal or something like Hyperterminal. I would also
> >add a keyboard interface.
> >
> >Thanks! > Try opencores.org, they have a number of cores and one is a video
controller.
>
> http://www.opencores.org/projects.cgi/web/vga_lcd
>
> If you only need text, you might be better off designing your own
and
> saving the logic. An 80x25 text display is very, very simple and
should
> not take much time to design. If you want, I might do it as an
exercise. :)
>
> Be aware that VGA uses ADC converters to drive the three colors.
You can
> kludge the interface from a digital output like this...
>
> http://www.fpga4fun.com/PongGame.html
>
> This sort of thing can give you up to 8 colors which is plenty for
a text
> display. You can also add a few more resistors (and outputs) and
have
> three or four levels on each output which can give you up to 64
> colors. Much beyond that and you will likely see problems with
quality. >
> Rick Collins
>
> rick.collins@a...
>
> Arius - A Signal Processing Solutions Company
> Specializing in DSP and FPGA design http://www.arius.com
> 4 King Ave 301-682-7772 Voice
> Frederick, MD 21701-3110 301-682-7666 FAX




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Re: Re: Simple Character CRT Core Needed - Arius - Rick Collins - Aug 31 22:50:00 2004

At 02:32 PM 8/31/2004, you wrote: >I had seen the listing at opencores and it seemed far too complex.
>At the moment I think I just want 80x25 but it also needs to do the
>control codes for a TV950 or ADM3a (switchable?) as some of the old
>software is configured and I can't seem to get it to change - Turbo
>Pascal and its TINST for example. I don't know why I can't get it
>to work but I think it has something to do with an error in the
>download. I had a large Fortran program that wouldn't run until I
>downloaded the compiler/linker and recompiled on the target.
>Curious... Well, I haven't used these programs in 20 years so it's
>possible I have forgotten some of the details.
>
>I bought the Xilinx Spartan-3 Starter Kit the other day (what a
>bargain for $100) and started to play with it last night. What do
>you know? There's a reason for the VGA connector on the board -
>there is a text mode VGA component included and it is ready to rock
>and roll. There's a ton of stuff that comes with this kit and,
>although a little small at 200k gates, $100 is not much tuition
>these days.

I guess you could do the full terminal emulation in hardware, but that is
normally done in software with the basic memory to raster conversion done
in hardware. The software writes the appropriate characters to the display
memory according to the commands that are received.

Perhaps I am misunderstanding what your CRT is doing. I was assuming that
you wanted a computer console CRT controller like the VGA card in a PC. Is
this instead intended to be a terminal emulation as if it had a serial
connection to the CPU? In that case, you can implement the terminal
commands in hardware, but that is very different from a CRT controller,
which is what I was pointing you to.

I have a VHDL UART emulation for a board that plugs into a PC/104 bus (same
as the PC ISA). The CPU thinks it is talking to a UART connected via a
serial port to another device (my board). But this requires much of the
work to be done in a CPU (which is also in the FPGA). If you are designing
a terminal emulation, this is similar to what you would need.
Rick Collins
Arius - A Signal Processing Solutions Company
Specializing in DSP and FPGA design http://www.arius.com
4 King Ave 301-682-7772 Voice
Frederick, MD 21701-3110 301-682-7666 FAX




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Re: Re: Simple Character CRT Core Needed - Ed Corter - Sep 1 0:05:00 2004


heres a verilog uart

you can strip it down and simplify it by finding the Tx and Rx state machines and making use of them descretely....

Peace

http://ca.geocities.com/artiedc/files/UartZip.zip

Ed Corter
Resume Page http://www.geocities.com/artiedc/ ---------------------------------




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Re: Re: Simple Character CRT Core Needed - John Kent - Sep 1 4:50:00 2004


Hi,

If you want to squeeze the VDU on with the T80, but want to have
intelligence
in the video display, you might consider cobbling the VDU in with a
small micro
like my Micro8/8a and write the video driver in the Micro8.

If you have the Xilinx Spartan3 starter board as well as Tony's board,
it sounds
like you could just about have an intelligent T80 based VDU on the
starter board.

The Starter board looks great by the way... I was inspired to make inquiries
at my local Xilinx agent today. Anyway ... Have a look around my web site:

http://members.optushome.com.au/jekent/FPGA.htm

The ADM3a was pretty basic ... I think it just honoured the basic control
characters and had an addressable cursor command. it should not be too hard
to write an intellegent VDU driver for it if you know what the command
set it.

I have some video drivers for a Thomas VDU written for the 6800.
You can fit my 6800 with UART in a XSA100 (100Kgate FPGA)
so you should be able to fit it comfortably on a 200Kgate Spartan 3
with a VDU.

John.

rtstofer wrote:

>I had seen the listing at opencores and it seemed far too complex.
>At the moment I think I just want 80x25 but it also needs to do the
>control codes for a TV950 or ADM3a (switchable?) as some of the old
>software is configured and I can't seem to get it to change - Turbo
>Pascal and its TINST for example. I don't know why I can't get it
>to work but I think it has something to do with an error in the
>download. I had a large Fortran program that wouldn't run until I
>downloaded the compiler/linker and recompiled on the target.
>Curious... Well, I haven't used these programs in 20 years so it's
>possible I have forgotten some of the details.
>
>I bought the Xilinx Spartan-3 Starter Kit the other day (what a
>bargain for $100) and started to play with it last night. What do
>you know? There's a reason for the VGA connector on the board -
>there is a text mode VGA component included and it is ready to rock
>and roll. There's a ton of stuff that comes with this kit and,
>although a little small at 200k gates, $100 is not much tuition
>these days. >

--
http://members.optushome.com.au/jekent




(You need to be a member of fpga-cpu -- send a blank email to fpga-cpu-subscribe@yahoogroups.com )

Re: Simple Character CRT Core Needed - rtstofer - Sep 1 10:10:00 2004


I was looking at the Map Report for the FPGA after the T80 core,
dual serial ports and the IDE interface are all mapped and the
complete system including monitor/boot ROM use well under 50% of the
resources. The system is about 92,000 equivalent gates out of about
300,000.

More important is Block RAM - here the 2k byte NoICE monitor uses
25% of available Block RAM. This leaves 48k bits available for
screen memory and a character generator and, if necessary, the
monitor could be eliminated and replaced with the 128 byte boot
code. Screen memory of 2000 characters with 10 bits/char plus a
character generator of 128 chars at 64 bits/char would require a
total 28192 bits - this should fit easily.

I figured that if a complete Z80, 2 serial ports and all the other
components would fit in less than half the space, it should be
possible to fit an ADM3A in the remainder. Maybe there would be room
for a PS/2 port for the keyboard or I could use one of the serial
ports.

A one chip solution (not counting external SRAM) is very appealing! --- In , John Kent <jekent@o...> wrote:
>
> Hi,
>
> If you want to squeeze the VDU on with the T80, but want to have
> intelligence
> in the video display, you might consider cobbling the VDU in with
a
> small micro
> like my Micro8/8a and write the video driver in the Micro8.
>
> If you have the Xilinx Spartan3 starter board as well as Tony's
board,
> it sounds
> like you could just about have an intelligent T80 based VDU on the
> starter board.
>
> The Starter board looks great by the way... I was inspired to make
inquiries
> at my local Xilinx agent today. Anyway ... Have a look around my
web site:
>
> http://members.optushome.com.au/jekent/FPGA.htm
>
> The ADM3a was pretty basic ... I think it just honoured the basic
control
> characters and had an addressable cursor command. it should not be
too hard
> to write an intellegent VDU driver for it if you know what the
command
> set it.
>
> I have some video drivers for a Thomas VDU written for the 6800.
> You can fit my 6800 with UART in a XSA100 (100Kgate FPGA)
> so you should be able to fit it comfortably on a 200Kgate Spartan 3
> with a VDU.
>
> John.
>
> rtstofer wrote:
>
> >I had seen the listing at opencores and it seemed far too
complex.
> >At the moment I think I just want 80x25 but it also needs to do
the
> >control codes for a TV950 or ADM3a (switchable?) as some of the
old
> >software is configured and I can't seem to get it to change -
Turbo
> >Pascal and its TINST for example. I don't know why I can't get
it
> >to work but I think it has something to do with an error in the
> >download. I had a large Fortran program that wouldn't run until
I
> >downloaded the compiler/linker and recompiled on the target.
> >Curious... Well, I haven't used these programs in 20 years so
it's
> >possible I have forgotten some of the details.
> >
> >I bought the Xilinx Spartan-3 Starter Kit the other day (what a
> >bargain for $100) and started to play with it last night. What
do
> >you know? There's a reason for the VGA connector on the board -
> >there is a text mode VGA component included and it is ready to
rock
> >and roll. There's a ton of stuff that comes with this kit and,
> >although a little small at 200k gates, $100 is not much tuition
> >these days.
> >
> >
> >
>
> --
> http://members.optushome.com.au/jekent




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Re: Re: Simple Character CRT Core Needed - John Kent - Sep 1 19:37:00 2004

That sounds cool.

A small micro, a UART, PS/2 interface and a VDU should fit no problem.
My VDU uses 6KBytes or 48Kbits of Block RAM. 2KB for the Text buffer,
2KB for the colour attributes and 2KB ??? (possibly 1K) for the character
generator.

You connect one of the UARTs back to back with the VDU UART and have
a separate SOC to control the Display. An ADM3a terminal driver won't take
much coding. You are going to have to do a little work though. The VDU micro
is going to require a small amount of RAM and ROM too ...

If your T80 is only using 33% of a 300K FPGA you could probably instantiate
a second copy of the T80 and UART, add the VDU and use that to drive the
display. I have an old Z80 board that has a built in ADM3a terminal
emulator ...
I may be able to dig up the code for that if you like ...
The PS/2 keyboard interface is available on my web site as well as open
cores.

My System68 sounds like it is not as efficiently coded as the T80, but
you could
certainly use that as well. Do you need some assistance putting it
together ?

John.

rtstofer wrote:

>I was looking at the Map Report for the FPGA after the T80 core,
>dual serial ports and the IDE interface are all mapped and the
>complete system including monitor/boot ROM use well under 50% of the
>resources. The system is about 92,000 equivalent gates out of about
>300,000.
>
>More important is Block RAM - here the 2k byte NoICE monitor uses
>25% of available Block RAM. This leaves 48k bits available for
>screen memory and a character generator and, if necessary, the
>monitor could be eliminated and replaced with the 128 byte boot
>code. Screen memory of 2000 characters with 10 bits/char plus a
>character generator of 128 chars at 64 bits/char would require a
>total 28192 bits - this should fit easily.
>
>I figured that if a complete Z80, 2 serial ports and all the other
>components would fit in less than half the space, it should be
>possible to fit an ADM3A in the remainder. Maybe there would be room
>for a PS/2 port for the keyboard or I could use one of the serial
>ports.
>
>A one chip solution (not counting external SRAM) is very appealing! >

--
http://members.optushome.com.au/jekent




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Re: Simple Character CRT Core Needed - rtstofer - Sep 1 20:26:00 2004


I probably won't start work on this until next week. I need to port
the BIOS from the PC using the PseudoSam assembler to the FPGA using
the MAC assembler. Unfortunately the source code syntax is
considerably different - a complete rewrite is required.

Today's effort was to implement a way to have the cold start loader
pick one of two BIOSs depending on a config switch. This will allow
me to write a developmental BIOS on the actual machine and not lunch
the whole thing.

I'm going to look further at what you have done. I had thought that
the internal ADM3A would just communicate over the internal 8 bit
bus and take data as a port. From the outside the code would just
stick a byte in a port just as though it was headed toward one of
the UARTs but with no need to check status (?).

One of my first problems is going to be quite difficult. Although
the Timing Report says this thing should run very fast, I haven't
been able to get it much over 14 MHz. I would like to get to
29.491200 MHz to match the standard VGA pixel rate for 640x480
(actually a little more than the 25 MHz normally used) and also have
a convenient baud rate divider. I'm not sure which part of the
system is having difficulties and I don't have any documentation
that says "Hey, this thing will run xxx MHz!". I could always cheat
and use a 29 MHz clock for the display and divide it in half for the
T80 but I would really rather have 29 MHz throughout.

If you have ideas about how I should proceed on the speed issue
please let me know. I am an absolute beginner with FPGAs and really
don't have a clue about how to tackle this - other than test signals
and a scope.

I'll keep in touch...

--- In , John Kent <jekent@o...> wrote:
> That sounds cool.
>
> A small micro, a UART, PS/2 interface and a VDU should fit no
problem.
> My VDU uses 6KBytes or 48Kbits of Block RAM. 2KB for the Text
buffer,
> 2KB for the colour attributes and 2KB ??? (possibly 1K) for the
character
> generator.
>
> You connect one of the UARTs back to back with the VDU UART and
have
> a separate SOC to control the Display. An ADM3a terminal driver
won't take
> much coding. You are going to have to do a little work though. The
VDU micro
> is going to require a small amount of RAM and ROM too ...
>
> If your T80 is only using 33% of a 300K FPGA you could probably
instantiate
> a second copy of the T80 and UART, add the VDU and use that to
drive the
> display. I have an old Z80 board that has a built in ADM3a
terminal
> emulator ...
> I may be able to dig up the code for that if you like ...
> The PS/2 keyboard interface is available on my web site as well as
open
> cores.
>
> My System68 sounds like it is not as efficiently coded as the T80,
but
> you could
> certainly use that as well. Do you need some assistance putting it
> together ?
>
> John.





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Re: Re: Simple Character CRT Core Needed - John Kent - Sep 2 3:37:00 2004

Hi rstofer,

(what is your first name ?)

My System09 will only run at 12.5MHz, but that is the basic E clock.
I'm nesting the decodes of the opcode register, in the state sequencer
which is not very efficient. I also use the ALU for everything including
indexing address calculations. It would probably work a bit faster if I
reduced the size of the mux on the ALU inputs and had a seperate
address adder for the addressing modes.

Floor planning the design would probably help too, but I don't have that
much time to play with it these days. I don't think there is a lot you
can do
with the industry standard 8 bit CPUs as they do not really allow you to
pipeline the instructions. I think my design had an address setup time
of around 30nSec and a data setup time on reads of about 20nsec
This left about 30nsec to access SRAM which is probably what
you need if you are runing ribbon cables to the SRAM.
(Tony uses 15nsec RAM)

640 x 480 you should work quite happily at 25MHz. Multisynch monitors
don't seem to be *that* fussy about the line and frame rate and you can
normally compensate by adjusting the monitor settings.
I run my system09 at half the pixel clock rate. It would be nice to run
it faster ... but what the hey ... if I want a faster computer I would
use my PC.

Looking at the code on the web, I noticed that I was using 19.8MHz
for the pixel clock rate (hence 64 characters across). At least that is what
it says in the documentation at the header of the code. I'm not sure the
documentation has kept pace with the actual design though ;-).
19.8MHz is a nice binary multiple of the baud clock. In later designs I
pushed it up to 25MHz and it still worked OK. I used a divide by 27
to get the correct baud rate clock.

To clear the bottom line of the screen when doing a line feed, you need
some smarts in the logic to clear the bottom line. Normally this is done
with
some sort of state machine as part of the line scan function.You also
need to do
some character decoding to handle the addressable cursor. It's doable
in hardware, but it's a lot easier and flexible to do it in software.
You also have
the advantage of being able to buffer incoming characters.

I'm waffling on here ... sorry ...

You need to set up the constraints file to check the propagation delays
in each section of code or use the simulator. I used to know how to do
it with web pack ISE 4.2 but the scheme has changed a little with later
releases of web pack. (I'm no expert either :-)

If you have not used the modeltech simulator, Its probably a good idea
to try it. You should be able to simulate a post placed and routed design
although so far I have only used it as a functional simulator to verify that
the CPU is executing the correct cycles which did not include the
propagation
delays in the design ... I'm sure others on the list can help you out
with that.

John.

rtstofer wrote:

>I probably won't start work on this until next week. I need to port
>the BIOS from the PC using the PseudoSam assembler to the FPGA using
>the MAC assembler. Unfortunately the source code syntax is
>considerably different - a complete rewrite is required.
>
>Today's effort was to implement a way to have the cold start loader
>pick one of two BIOSs depending on a config switch. This will allow
>me to write a developmental BIOS on the actual machine and not lunch
>the whole thing.
>
>I'm going to look further at what you have done. I had thought that
>the internal ADM3A would just communicate over the internal 8 bit
>bus and take data as a port. From the outside the code would just
>stick a byte in a port just as though it was headed toward one of
>the UARTs but with no need to check status (?).
>
>One of my first problems is going to be quite difficult. Although
>the Timing Report says this thing should run very fast, I haven't
>been able to get it much over 14 MHz. I would like to get to
>29.491200 MHz to match the standard VGA pixel rate for 640x480
>(actually a little more than the 25 MHz normally used) and also have
>a convenient baud rate divider. I'm not sure which part of the
>system is having difficulties and I don't have any documentation
>that says "Hey, this thing will run xxx MHz!". I could always cheat
>and use a 29 MHz clock for the display and divide it in half for the
>T80 but I would really rather have 29 MHz throughout.
>
>If you have ideas about how I should proceed on the speed issue
>please let me know. I am an absolute beginner with FPGAs and really
>don't have a clue about how to tackle this - other than test signals
>and a scope.
>
>I'll keep in touch...
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Re: Simple Character CRT Core Needed - rtstofer - Sep 2 8:58:00 2004


John,

I am starting to look at clock dividers - like you say, if I need a
lot of speed I can use my PC. The next project is a Pascal P4
implementation and I expect a lot more from the chip but I'll have
the advantage (?) of a clean piece of paper and the ability to throw
hardware at the interpreter until it is highly parallel. We'll
see...

If I can get a clock divider to work then that's the way it will
stay. The timing report shows a minimum period of just under 30 nS
and if I add something for the SRAM (say 15 nS) and another 15 nS
for slop I come up with 60 nS or about 16 MHz and I am running 14.7
so I may have maxed out without doing a lot more work.

Richard

--- In , John Kent <jekent@o...> wrote:
> Hi rstofer,
>
> (what is your first name ?)
>
> My System09 will only run at 12.5MHz, but that is the basic E
clock.
> I'm nesting the decodes of the opcode register, in the state
sequencer
> which is not very efficient. I also use the ALU for everything
including
> indexing address calculations. It would probably work a bit faster
if I
> reduced the size of the mux on the ALU inputs and had a seperate
> address adder for the addressing modes.
>
> Floor planning the design would probably help too, but I don't
have that
> much time to play with it these days. I don't think there is a lot
you
> can do
> with the industry standard 8 bit CPUs as they do not really allow
you to
> pipeline the instructions. I think my design had an address setup
time
> of around 30nSec and a data setup time on reads of about 20nsec
> This left about 30nsec to access SRAM which is probably what
> you need if you are runing ribbon cables to the SRAM.
> (Tony uses 15nsec RAM)
>
> 640 x 480 you should work quite happily at 25MHz. Multisynch
monitors
> don't seem to be *that* fussy about the line and frame rate and
you can
> normally compensate by adjusting the monitor settings.
> I run my system09 at half the pixel clock rate. It would be nice
to run
> it faster ... but what the hey ... if I want a faster computer I
would
> use my PC.
>
> Looking at the code on the web, I noticed that I was using 19.8MHz
> for the pixel clock rate (hence 64 characters across). At least
that is what
> it says in the documentation at the header of the code. I'm not
sure the
> documentation has kept pace with the actual design though ;-).
> 19.8MHz is a nice binary multiple of the baud clock. In later
designs I
> pushed it up to 25MHz and it still worked OK. I used a divide by 27
> to get the correct baud rate clock.
>
> To clear the bottom line of the screen when doing a line feed, you
need
> some smarts in the logic to clear the bottom line. Normally this
is done
> with
> some sort of state machine as part of the line scan function.You
also
> need to do
> some character decoding to handle the addressable cursor. It's
doable
> in hardware, but it's a lot easier and flexible to do it in
software.
> You also have
> the advantage of being able to buffer incoming characters.
>
> I'm waffling on here ... sorry ...
>
> You need to set up the constraints file to check the propagation
delays
> in each section of code or use the simulator. I used to know how
to do
> it with web pack ISE 4.2 but the scheme has changed a little with
later
> releases of web pack. (I'm no expert either :-)
>
> If you have not used the modeltech simulator, Its probably a good
idea
> to try it. You should be able to simulate a post placed and routed
design
> although so far I have only used it as a functional simulator to
verify that
> the CPU is executing the correct cycles which did not include the
> propagation
> delays in the design ... I'm sure others on the list can help you
out
> with that.
>
> John.





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Re: Simple Character CRT Core Needed - rtstofer - Sep 2 17:35:00 2004


John,

I stole the design of your clock divider with the following: library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

--*****************************
-- Added the following library
--*****************************

library UNISIM;
use UNISIM.vcomponents.all;

entity VDU is
Port ( Reset_n : in std_logic;
Clk_in : in std_logic;
CPU_Clk_out : out std_logic);
end VDU;

architecture Behavioral of VDU is

signal Divider : std_logic_vector(1 downto 0);

component BUFG
port (
i: in std_logic;
o: out std_logic
);
end component;

begin

process (Reset_n, Clk_in)
begin
if Reset_n = '0' then
Divider <= (others => '0');
elsif Clk_in'event and Clk_in = '1' then
Divider <= Divider + 1;
end if;
end process;

clk_buffer: BUFG port map (
i => Clk_in,
o => CPU_Clk_out
);

end Behavioral;

and at the top level instantiated it with:

u5 : entity work.VDU
port map (
Reset_n => Reset_s,
Clk_in => SysClk,
CPU_Clk_out => Clk);

SysClk is the signal coming in to the chip from the oscillator and
this is the only place it is connected. Clk is used everywhere.

Now the question: throughout your system you have used falling clock
edges while the T80 core uses rising edges. Is this a difference
worth noting?

The reason I ask is that the divider doesn't work if I use ANY
signal other that Clk_in as the input to the BUFG. If I use 'not
Clk_in' or 'Divider(0)' the system does not function and by that I
mean that even the divider driving the LED (which uses Clk) is not
functioning. I can only assume that there is no clock coming out of
VDU. I haven't brought it to a pin to prove it because I figured
that if the LED doesn't blink there isn't much in the way other than
a missing clock.

It's obvious I have messed up - do you have any idea how?

Richard




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Re: Re: Simple Character CRT Core Needed - John Kent - Sep 3 3:42:00 2004

Hi Richard,

rtstofer wrote:
Snip... snip

>SysClk is the signal coming in to the chip from the oscillator and
>this is the only place it is connected. Clk is used everywhere.
>
>Now the question: throughout your system you have used falling clock
>edges while the T80 core uses rising edges. Is this a difference
>worth noting? >
Yes ... System09 clocks on the falling edge. I think it's simply a
matter of changing all the occurrences of

if clk'event and clk=0 then
to
if clk'event and clk=1 then

That's assuming data is valid on the rising edge of the clock.
The SystemXX family also use R/W and the clock, where as I think the T80
uses separate RD and WR signals .... I use a mux on all the data inputs
so the RD does not matter ... data is valid if you select a device.

>The reason I ask is that the divider doesn't work if I use ANY
>signal other that Clk_in as the input to the BUFG. If I use 'not
>Clk_in' or 'Divider(0)' the system does not function and by that I
>mean that even the divider driving the LED (which uses Clk) is not
>functioning. I can only assume that there is no clock coming out of
>VDU. I haven't brought it to a pin to prove it because I figured
>that if the LED doesn't blink there isn't much in the way other than
>a missing clock.
>
>It's obvious I have messed up - do you have any idea how? >
The only thought I had was if you have a synchronous reset somewhere
that held the
divider reset, hence no clock to release it .... But looking at your
code, that does
not appear to be the problem.

From my observation of the FPGA lists there is bit of a holy war,
whether to use
synchronous or asynchronous resets. I tended to swap arount a bit, which
probably
makes things worse.

BTW. I received my Xilinx starter kit today .... the FPGA looks very small
It does not look like it has enough pins on it to do everything :-)

You mentioned that there was a heap of IP that came with the board ...
I had a quick look on the starter disk but only saw applications notes
in PDF
format. I have not looked on the ISE 6.2 disks.

John.

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Re: Simple Character CRT Core Needed - rtstofer - Sep 3 9:38:00 2004

> I had a quick look on the starter disk but only saw applications
notes
> in PDF
> format. I have not looked on the ISE 6.2 disks.

There are a number of ZIP files in D:\FILES\APPNOTES.

I wasn't paying attention when I followed the link from the CD to
Xilinx: The IP goodies are in the MicroBlaze Master System ZIP file
at http://www.xilinx.com/products/spartan3/s3boards.htm#RF

There are quite a few uncommited pins available on both the A2 and
B1 edge connector. As I compare it to the B5 board and my T80
implementation, the SRAM takes 2-20 pin connectors on the B5 and it
is built in to the starter kit, the dip switches and LEDs take
another 2-20 pin connectors and they are built in (not an equal
number but sufficient), the IDE interface takes 2-20 pin connectors
and, with effort, should run off the A2 connector, the dual UARTS
take 1-20 pin connector and that could run off the B1 connector
(although 1 serial already exists on the starter board) and that
leaves 1-20 pin connector open on the B5 that doesn't exist on the
starter kit. However, the starter kit includes the PS/2 and VGA
ports.

I don't think it is an even match but it's close. I really haven't
had time to play with the board - I plugged it in, watched the
lights flash and checked the VGA output and put it back in the box.
I am workiing pretty much full time on the B5.

I think you may be on to something with the reset idea - I'll check
it out. The idea obviously works, it is my implementation that is
wrong. >
> John.
>
> --
> http://members.optushome.com.au/jekent




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Re: Re: Simple Character CRT Core Needed - John Kent - Sep 4 0:51:00 2004

Hi Richard,

rtstofer wrote:

>I wasn't paying attention when I followed the link from the CD to
>Xilinx: The IP goodies are in the MicroBlaze Master System ZIP file
>at http://www.xilinx.com/products/spartan3/s3boards.htm#RF >
Yes ... I followed that link too, but I thought all the code there was
comercial.
There was a 6845 CRTC listed, but there is still a bit of work to get it
going as a
complete Intelligent terminal.

>There are quite a few uncommited pins available on both the A2 and
>B1 edge connector. As I compare it to the B5 board and my T80
>implementation, the SRAM takes 2-20 pin connectors on the B5 and it
>is built in to the starter kit, the dip switches and LEDs take
>another 2-20 pin connectors and they are built in (not an equal
>number but sufficient), the IDE interface takes 2-20 pin connectors
>and, with effort, should run off the A2 connector, the dual UARTS
>take 1-20 pin connector and that could run off the B1 connector
>(although 1 serial already exists on the starter board) and that
>leaves 1-20 pin connector open on the B5 that doesn't exist on the
>starter kit. However, the starter kit includes the PS/2 and VGA >ports. >
You have to be carefull with the starter kit in that many of the A and B
connector pin-outs
are shared with the SRAM and might not be usable for expansion. The SRAM
on the B5 board
is 16 bit and because of the limitted number of pins on the 20 pin
headers you can only really
fit 256 K bytes or 128KWords.

The B5-CPU-IO-Board only takes one 20 pin port but provides more I/O:
ie. RS232,
PS2 Keyboard, PS2 Mouse, 6bit / 64 Colour VGA, and buzzer. I don't make
much use
of LEDs switches and Displays so I'm quite happy having the option of
leaving them off
the B5 board.

Maybe a suggestion for future improvements to the B5-CPU-IO would be to
use the RTS and
CTS signals as a jumperable secondary RS232 TXD/RXD connection on the
second DB9
connector.

The starter board has 1Mbyte of SRAM with a 32 bit data bus (2 x 16
bits) with upper and
lower byte controls on each 16 bit data path. This makes it ideal for 32
bit applications but
means you are using up an number of connector and FPGA pins if you are
only implementing
8 bit designs.

The Starter board manual talks a bit about using configuration Flash for
applications code.
Presumably you have to code some serial loader to read the Config Flash
into SRAM.

>I don't think it is an even match but it's close. I really haven't
>had time to play with the board - I plugged it in, watched the
>lights flash and checked the VGA output and put it back in the box.
>I am workiing pretty much full time on the B5. >
The B5 board is better set up for expansion.

>I think you may be on to something with the reset idea - I'll check
>it out. The idea obviously works, it is my implementation that is
>wrong. Ok ... I'm not sure what else to check without you sending me the code.

I've been working on putting my system09 with VDU into the Xilinx
starter board and
I've come across a few problems. The 200K gate spartan 3 only has 12
block RAMs
where as the 300K gate Spartan 2e (B5 board) has 16 and the 200K Gate
Spartan 2+
(B3 board) has 14 Block RAMs (I think).

My System09 monitor ROM uses 2Kbytes or 4block RAMs The VDU uses another
4 for the character RAM, 4 for the Attribute RAM and 2 for the Character
Generator.
= 14 block RAM ... rats !

I tried coding the character generator so that it used Slices rather
than Block RAM,
but then that over ran the slice allocation by 4% ie 104% of slices used.
I tried pulling everything out but the PS2 keyboard, UART, VDU and CPU,
but it
just won't fit.

The only thing I can do now is to reduce the Attribute RAM to 2K x 4bits
and only
allow a foreground colour attribute. I could perhaps use the 7th data
bit of the
character RAM as reverse video.

I could re-write the VDU to share the SRAM and use the Block RAM as a line
scan buffer. That way the CPU could write directly into video memory.
The problem with that is that if you want to use the T80 with it you need to
be able to insert idle bus cycles.

I'm a bit conscious of monopolising this list.
It might be worth taking this discussion off line unless others are
interested.

John.

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Re: Simple Character CRT Core Needed - rtstofer - Sep 4 9:27:00 2004

I wouldn't worry about filling up the list - this is the only
project going on at the moment.

When I looked at the tables for the edge connectors on the starter
board, I counted the uncommitted pins and it looked reasonable for a
direct replacement of the B5 as far as my T80 is concerned - but it
is certainly not equivalent. The B5 is far more general and a much
larger device.

I have no idea what I will do with the starter board but the Pascal
P4 project would be more interesting as a 32 bit design. In fact,
32 bits might be nice because it gives a useful integer range,
eliminates multi-byte operations and implies that every register can
address the entire memory space.

This weeks project is to get the second drive on the IDE channel up
and running. It was supposed to work by magic - it doesn't.

MicroBlaze is usually a commercial IP. I thought it strange that it
was included in the starter kit but my first interest was in the VDU
IP although yours is more applicable. Anyway, the code is available
so I grabbed it.






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Re: Re: Simple Character CRT Core Needed - John Kent - Sep 4 22:19:00 2004

Hi Richard

rtstofer wrote:

>I wouldn't worry about filling up the list - this is the only
>project going on at the moment.
>
>When I looked at the tables for the edge connectors on the starter
>board, I counted the uncommitted pins and it looked reasonable for a
>direct replacement of the B5 as far as my T80 is concerned - but it
>is certainly not equivalent. The B5 is far more general and a much
>larger device. >
The starter board appears to be a 256 pin BGA where as the B5 is a 208
pin QFP
so the starter kit in theory should have more pins.

>I have no idea what I will do with the starter board but the Pascal
>P4 project would be more interesting as a 32 bit design. In fact,
>32 bits might be nice because it gives a useful integer range,
>eliminates multi-byte operations and implies that every register can
>address the entire memory space. >
Is the Pascal P4 project a Pcode machine ?

>This weeks project is to get the second drive on the IDE channel up
>and running. It was supposed to work by magic - it doesn't.
>
>MicroBlaze is usually a commercial IP. I thought it strange that it
>was included in the starter kit but my first interest was in the VDU
>IP although yours is more applicable. Anyway, the code is available
>so I grabbed it. I was up until 3:30 am last night working on the VDU with a stripped
back System09.
It is a very tight fit in the XC3S200. I've got the 80 x 25 display
working of sorts although
I can't get a cracker out of the CPU UART, so I'm not sure what is going
on there.
I'll have to take a closer look at the SRAM. The Buttons are actually
active high rather
than the usual active low.

I pulled the attribute RAM out of the design, but then realised from the
literature that the
Spartan 3 Block RAM is actually 2K * 9 bits, rather than 512 * 8 bits so
I'll have to
re-instate it. Hopefully it will save a few slices on data bus multiplexers.

I did not see the Microblaze code, but I guess it must be on the CD
somewhere.

John.

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Re: Simple Character CRT Core Needed - rtstofer - Sep 4 23:31:00 2004

In looking through the MicroBlaze Master Kit file, I see a lot of C
code for execution on the MicroBlaze but none of the design files.
I think that bit is for sale in the Embedded Design Kit for a mere
$495. I'll have to think about that - it's pretty expensive.

Yes the P4 system is a P code machine. Many years ago I used the
UCSD Pascal system which was Niklaus Wirth's Pascal on steroids. As
I recall, I didn't think much of the file system in concept but it
did function. What I did like about the system was the total
integration of the compiler, assembler, editor and run time. I
added a couple of graphic devices to the interpreter and had a fine
time with a Tektronix 4013(?) Graphics Terminal and a CalComp drum
plotter. Unfortunately, I discarded the source listings several
years ago - stupid! Not to worry, I just got another copy of the
original Wirth code for the compiler and interpreter. Not the UCSD
system but a start - the same start they had at UCSD.

Western Digital made a chip to run the UCSD system but it never went
anywhere. Seems the university cancelled all the user licenses and
sold the system to a company that still markets it in a small-time
way. Too bad, at the time it was the best thing going.

From a hardware point of view the original P4 system ran on a CDC
6400 with a 60 bit word. But what I see is an opportunity to design
hardware specifically for a stack oriented machine with an unlimited
number of levels of indirection for variable references. What a
trip!

I hope you post your new VDU - I am still looking in to doing that
if I ever get the compact flash running on the IDE channel. I'm
missing something; a hard disk plugged in to the cable works
perfectly but the CF balks. I'm reasonably certain I have an issue
with the command sequencing but it'll take time to work it out.
That and a long read of the 125 page interface manual!






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Re: Re: Simple Character CRT Core Needed - John Kent - Sep 5 1:48:00 2004

Hi Richard ...

Well I got System09 running on the starter board with 80 x 25 character
display with colour
and chunky graphics to boot :-) It uses 1842 slices out of 1920, so as I
said before it's a
tight fit. I just have to write some display driver software. I have a
Monitor ROM for a
memory mapped 64 x 16 display. It will just be a matter of modifying it
a little to access
memory through the registers rather than writing directly into memory.
I'll put the code up
on the web site when I get the monitor working properly. I'm currently
just using the RS232
port to talk to the system. Unfortunately the only PS/2 keyboard I have
is attached to this
computer :-(

rtstofer wrote:

>In looking through the MicroBlaze Master Kit file, I see a lot of C
>code for execution on the MicroBlaze but none of the design files.
>I think that bit is for sale in the Embedded Design Kit for a mere
>$495. I'll have to think about that - it's pretty expensive. >
I thought that might have been the case.

>Yes the P4 system is a P code machine. Many years ago I used the
>UCSD Pascal system which was Niklaus Wirth's Pascal on steroids. As
>I recall, I didn't think much of the file system in concept but it
>did function. What I did like about the system was the total
>integration of the compiler, assembler, editor and run time. I
>added a couple of graphic devices to the interpreter and had a fine
>time with a Tektronix 4013(?) Graphics Terminal and a CalComp drum
>plotter. Unfortunately, I discarded the source listings several
>years ago - stupid! Not to worry, I just got another copy of the
>original Wirth code for the compiler and interpreter. Not the UCSD
>system but a start - the same start they had at UCSD. >
I had a small integer only pascal for the 6800. I disassembled it, and
found it was largely
Pcode. The Pcode interpreter was only 1 K or so, so should be quite
ammenable to coding
in VHDL. The software dates back to the early 80's or possibly before. I
think there might
have been a series of articles in Byte magazine around that time on
Pascal Pcode compilers.
I think it might have inspired a number of budding compiler writers to
write their own version.

>Western Digital made a chip to run the UCSD system but it never went
>anywhere. Seems the university cancelled all the user licenses and
>sold the system to a company that still markets it in a small-time
>way. Too bad, at the time it was the best thing going. >
I remember seeing that advertised but never had much to do with it.

>>From a hardware point of view the original P4 system ran on a CDC
>6400 with a 60 bit word. But what I see is an opportunity to design
>hardware specifically for a stack oriented machine with an unlimited
>number of levels of indirection for variable references. What a
>trip! >
The Signetics 2650 used to have indirect addressing in it instruction
set. I think it used the MSB
of the 16 bit address as an indirect bit, which meant it could only
address 32K bytes of memory.

>I hope you post your new VDU - I am still looking in to doing that
>if I ever get the compact flash running on the IDE channel. I'm
>missing something; a hard disk plugged in to the cable works
>perfectly but the CF balks. I'm reasonably certain I have an issue
>with the command sequencing but it'll take time to work it out.
>That and a long read of the 125 page interface manual! I've written the VDU for the Spartan 3 and RAMB16_S9 which is not
available on the
Spartan 2 (I don't think). I will be a matter of back tracking and
re-instating the RAMB4
version of the Character ROM and RAM buffers.

I wrote some drivers for System68 to read and write single sectors. I
had to modify the
attribute registers for 8 bit operation. The code is on my web site ....

http://members.optushome.com.au/jekent/system68/index.htm

look half way down the page for "cf.zip" ... it might give you a few clues.

Also be careful with the access time for flash. It needs a minimum
access time of 100nSec.
Also I found it needed some "breathing time" between accesses. If you
try pushing it
too hard it won't work. I write a very simple 16 bit micro with one or
two clock cycles
per instruction. I ran it at 10 MHz but for some reason it would not
access the CF.
The CF kept reverting to the reset mode.
My System 68 which took a few more bus cycles to access it, worked fine.

Tony Burch had a state sequencer for reading and writing CF, but I could
never
get it to work. I think Tony was only running it at 1MHz where as I was
trying
to run it much faster which might have been the problem. I had a Dickens
of a
time trying to get it going for some one on one of these lists, who was
trying to
use it for a university project. The idea of the Micro16 was to provide
a bare
bones CPU that would replace the state machine.

John.

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Re: Simple Character CRT Core Needed - rtstofer - Sep 5 10:25:00 2004


John,

As implemented today, the T80 takes: Design Summary
--------------
Number of errors: 0
Number of warnings: 4
Logic Utilization:
Number of Slice Flip Flops: 596 out of 6,144 9%
Number of 4 input LUTs: 2,417 out of 6,144 39%
Logic Distribution:
Number of occupied Slices: 1,455 out of
3,072 47%
Number of Slices containing only related logic: 1,455 out of
1,455 100%
Number of Slices containing unrelated logic: 0 out of
1,455 0%
*See NOTES below for an explanation of the effects of
unrelated logic
Total Number 4 input LUTs: 2,609 out of 6,144 42%
Number used as logic: 2,417
Number used as a route-thru: 128
Number used for Dual Port RAMs: 64
(Two LUTs used per Dual Port RAM)
Number of bonded IOBs: 104 out of 142 73%
IOB Flip Flops: 9
Number of Block RAMs: 4 out of 16 25%
Number of GCLKs: 1 out of 4 25%
Number of GCLKIOBs: 1 out of 4 25%

Total equivalent gate count for design: 91,058
Additional JTAG gate count for IOBs: 5,040
Peak Memory Usage: 82 MB

As I said earlier, there seems to be quite a bit of space left for
the VDU.

You are correct, Tony Burch used a 1 MHz clock with the CF. I had
thought that since the cycle times were acceptable to an older IDE
drive that the CF would surely work. You bring up an interesting
point, maybe I should slow down the clock, increase the access times
and see what happens.

I am using 16 bit data transfers with the high order 8 bits always
0 - the drives are so large that giving up space was no problem
compared to the issue of converting back and forth from a 16 bit
register to an 8 bit bus. I can do it, of course, but for a first
attempt, it didn't seem worth the complication. For whatever
reason, the IDE drive returned an error when I tried to set the
feature for 8 bit transfers. I just wanted CP/M to run - ugly would
be acceptable.

Richard




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Re: Re: Simple Character CRT Core Needed - John Kent - Sep 5 12:14:00 2004

Hi Richard,

It's past 3:00 am and I need to get to bed.
I've put up my work so far up on my web site.

http://members.optushome.com.au/jekent/Spartan3/index.html

It runs my KBug9 monitor and displays stuff
on both the serial port and the VDU.
It should handle inputs from either the serial port
or the keyboard. I have not tested the keyboard although
I have not changed it from the B5 board, so it should still
work. The serial port runs at 57.6 Kbaud 8 data 1 stop bit.

There is a problem with the way I scroll the screen up.
because 80 x 25 = 2000 and not 2048 some funny things
happen to the alignment of the columns ...
(its hard to explain the effect without demonstating it)
I have a Column address offset register but I think there
are problems when the offset gets too large.

I've implemented a colour attribute register as well as
chunky graphics and flashing characters, but the Video
driver does not have any escape sequences to set it.
I have some bresenham line drawing routines for the 6800
and 6809 somewhere. I was using an old SubLogic
3D wire frame graphics routine for playing 3D games on
my old 6809 system. Would be rather neat to hard code
it in VHDL.

I have not implemented the full ADM-3A command set.
There are still a few control characters missing.

I also need a terminal mode so that the monitor does not
try to execute keyboard commands.

rtstofer wrote:

>As I said earlier, there seems to be quite a bit of space left for
>the VDU.
>
>You are correct, Tony Burch used a 1 MHz clock with the CF. I had
>thought that since the cycle times were acceptable to an older IDE
>drive that the CF would surely work. You bring up an interesting
>point, maybe I should slow down the clock, increase the access times
>and see what happens. >
Yep, give it a try ...

>I am using 16 bit data transfers with the high order 8 bits always
>0 - the drives are so large that giving up space was no problem
>compared to the issue of converting back and forth from a 16 bit
>register to an 8 bit bus. I can do it, of course, but for a first
>attempt, it didn't seem worth the complication. For whatever
>reason, the IDE drive returned an error when I tried to set the
>feature for 8 bit transfers. I just wanted CP/M to run - ugly would
>be acceptable. >
The Compact Flash data sheet describes an attribute register,
that you can program for 8 bit transfers. I'm not sure that IDE drives
have that.

John.

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Re: Simple Character CRT Core Needed - rtstofer - Sep 5 19:17:00 2004


I downloaded your project and put it in the starter board. I see
what you mean about the display - kind of strange. Nevertheless, a
lot of things work very well.

Stranger is the fact I can not get it to synthesize. I changed the
unisym library statements slightly to eliminate the red '?' marks in
the files list:

library UNISIM;
use UNISIM.VComponents.all;

but it still doesn't synthesize. It runs through the process,
writes a reasonable Synthesis Report, no errors, etc. but the step
continues to have a '?'. Any attempt to create the programming file
results in nothing happening.
--- In , John Kent <jekent@o...> wrote:
> Hi Richard,
>
> It's past 3:00 am and I need to get to bed.
> I've put up my work so far up on my web site.
>
> http://members.optushome.com.au/jekent/Spartan3/index.html
>
> It runs my KBug9 monitor and displays stuff
> on both the serial port and the VDU.
> It should handle inputs from either the serial port
> or the keyboard. I have not tested the keyboard although
> I have not changed it from the B5 board, so it should still
> work. The serial port runs at 57.6 Kbaud 8 data 1 stop bit.
>
> There is a problem with the way I scroll the screen up.
> because 80 x 25 = 2000 and not 2048 some funny things
> happen to the alignment of the columns ...
> (its hard to explain the effect without demonstating it)
> I have a Column address offset register but I think there
> are problems when the offset gets too large.
>
> I've implemented a colour attribute register as well as
> chunky graphics and flashing characters, but the Video
> driver does not have any escape sequences to set it.
> I have some bresenham line drawing routines for the 6800
> and 6809 somewhere. I was using an old SubLogic
> 3D wire frame graphics routine for playing 3D games on
> my old 6809 system. Would be rather neat to hard code
> it in VHDL.
>
> I have not implemented the full ADM-3A command set.
> There are still a few control characters missing.
>
> I also need a terminal mode so that the monitor does not
> try to execute keyboard commands.
>
> rtstofer wrote:
>
> >As I said earlier, there seems to be quite a bit of space left
for
> >the VDU.
> >
> >You are correct, Tony Burch used a 1 MHz clock with the CF. I
had
> >thought that since the cycle times were acceptable to an older
IDE
> >drive that the CF would surely work. You bring up an interesting
> >point, maybe I should slow down the clock, increase the access
times
> >and see what happens.
> >
> >
> >
> Yep, give it a try ...
>
> >I am using 16 bit data transfers with the high order 8 bits
always
> >0 - the drives are so large that giving up space was no problem
> >compared to the issue of converting back and forth from a 16 bit
> >register to an 8 bit bus. I can do it, of course, but for a
first
> >attempt, it didn't seem worth the complication. For whatever
> >reason, the IDE drive returned an error when I tried to set the
> >feature for 8 bit transfers. I just wanted CP/M to run - ugly
would
> >be acceptable.
> >
> >
> >
> The Compact Flash data sheet describes an attribute register,
> that you can program for 8 bit transfers. I'm not sure that IDE
drives
> have that.
>
> John.
>
> --
> http://members.optushome.com.au/jekent




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Re: Re: Simple Character CRT Core Needed - John Kent - Sep 5 23:21:00 2004

I take it you downloaded the .mcs file to the board.
I'm using Web pack ISE 6.2.03i.
The project file probably won't work for anything else ....

I think the UNISIM library is only for simulating the Xilinx library
components.
The red question marks for RAMB16_S9 don't seem to matter
Web pack appears to resolve that when you synthesize the code.

oh ..... you have to be careful of the auto make in Web pack.
Note that I'm probably about 10 hours ahead of you ...
If it preseves the time date stamp on the zip files, it might mess up the
auto make feature in Web Pack. I remember someone else complaining
about the make feature doing some strange things because they were
a few hours behind me. The Binary files were older that the source files
so Web pack thought the binaries were out of date :-)

Try loading and saving all the files again so that they have your
date-time on them.

I included some of the old files using the RAMB4 modules for the Spartan 2.
I might have changed a few of the architecture signals, so I need to
clean them
up abit eg. make ram2k.vhd into ram2k_b4.vhd and so on.

The funny scroll affect may have something to do with the way I did the
maths for the
Vertical offset register ... I multiply the row address by 5 then shift
it up 4 bits (mult by 80)
then add it to the horizontal column address to calculate the address in
memory.
In the software driver I simply increment the vertical offset register.
My brain is not working
at the moment, but there might be something wrong with doing that.

Once I get the bugs out of the display with system09 I'll try porting it
back to the
Spartan 2 board, so you can integrate it with your T80. rtstofer wrote:

>I downloaded your project and put it in the starter board. I see
>what you mean about the display - kind of strange. Nevertheless, a
>lot of things work very well.
>
>Stranger is the fact I can not get it to synthesize. I changed the
>unisym library statements slightly to eliminate the red '?' marks in
>the files list:
>
>library UNISIM;
>use UNISIM.VComponents.all;
>
>but it still doesn't synthesize. It runs through the process,
>writes a reasonable Synthesis Report, no errors, etc. but the step
>continues to have a '?'. Any attempt to create the programming file
>results in nothing happening. >
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Re: Simple Character CRT Core Needed - rtstofer - Sep 6 0:37:00 2004


Well, i fried my brain earlier on Margaritas but now that I am up to
semicomatose I see what you mean. It syntesizes just fine now that
the time/date stamps are past. Time zones, another in a long list
of lessons learned...

I'm using the same Web Pack so no issues there but I had downloaded
the .mcs file for the test. I never knew whether the little red
boxes meant anything, I just worked in a direction to make them go
away!

If there was more memory, I wonder if a look-up table would be a
faster way to get the memory address for the start of each row. And
maybe a way to barrel-shift the lookup table as the screen scrolls.
Or just a pointer to the point to the table entry that contains the
address of the first line. Then just add modulo 25 like a circular
buffer. But, I fear this design is getting a little tight! Giving
up 100k gates is a difficult thing. I also wish they had positioned
the power inlet centered between the serial and VGA connectors -
mine collides badly with the VGA plug.

On the 25 line thing: I don't know for sure about the ADM3A but I
think it has 24 lines. The Televideo 950 had a 25th line for status
information but it didn't scroll along with the others. This was
useful for function key prompts. Of course, it also has 4 pages of
screen memory and a full blown microprocessor to process the command
sequences which are quite extensive.

I am really looking forward to seeing this work on the Spartan II
although I must admit it is pretty clean on the Spartan III. I
should be able to port it in with very little difficulty.

Of course, the CF was supposed to be a drop-in thing as well...






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Re: Re: Simple Character CRT Core Needed - John Kent - Sep 6 14:46:00 2004

I'm taking a bit of a break. After a few 3:00 am nights I think I owe it
to myself.

I remember using a BeeHive terminal back in the early 80s. That also had
24 lines
with an optional 25th status line that you could enable or disable. I
think it was used
to report things like the baud rate, auxillary port status and so on. I
think it might have
had a number of screen pages too.

I'm not sure if 24 lines makes the circular buffer wrap around any easier.
I don't think you need a barrel shifter to offset the character rows,
just an offset on the row counter. Thats what I have done but when
the offset register gets to large or wraps around to zero, the offset
calculation
goes wrong and you get some modulo counter offset. I've just got to look
a little closer at how I've done offset.

Also, I need a better character generator. Characters are 8 pixels x 8pixels
and I have two scan lines per character row which does not leave much space
between characters on different rows. It would be nice to have an 8 x 12
pixel
character generator, but then the ROM would double in size, which may be
a problem for the Spartan 2 board.

John.

rtstofer wrote:

>If there was more memory, I wonder if a look-up table would be a
>faster way to get the memory address for the start of each row. And
>maybe a way to barrel-shift the lookup table as the screen scrolls.
>Or just a pointer to the point to the table entry that contains the
>address of the first line. Then just add modulo 25 like a circular
>buffer. But, I fear this design is getting a little tight! Giving
>up 100k gates is a difficult thing. I also wish they had positioned
>the power inlet centered between the serial and VGA connectors -
>mine collides badly with the VGA plug.
>
>On the 25 line thing: I don't know for sure about the ADM3A but I
>think it has 24 lines. The Televideo 950 had a 25th line for status
>information but it didn't scroll along with the others. This was
>useful for function key prompts. Of course, it also has 4 pages of
>screen memory and a full blown microprocessor to process the command
>sequences which are quite extensive.
>
>I am really looking forward to seeing this work on the Spartan II
>although I must admit it is pretty clean on the Spartan III. I
>should be able to port it in with very little difficulty.
>
>Of course, the CF was supposed to be a drop-in thing as well...
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Re: Simple Character CRT Core Needed - rtstofer - Sep 6 20:46:00 2004


By default, the Televideo 950 also uses the 25th line for status but
it can be overwritten with ESC f <message up the 80 chars> <CR>. I
don't see this as important although I did use it with one of the
screen oriented editors.

I'm getting a little burned out at the moment as well. I just
finished populating a PCB with dual 5 in, 3 out RS232 drivers for
the 2 COM ports and those little SSOP pkgs are a chore to solder.
In retrospect, I should have included the VGA R/2R, connector and
PS/2 Port at the same time. I'm also tryng to come up with a nice
way to package the system. I think it is going to look like a cube
of PCBs attached to Plexiglass sheets about 6" square with standoff
posts between the sheets. I have been looking at the idea of just
folding things together. I have also toyed with the idea of
stuffing the whole thing in a PC Tower case. Just yank the
motherboard, mount all the PCBs and call it good. --- In , John Kent <jekent@o...> wrote:
> I'm taking a bit of a break. After a few 3:00 am nights I think I
owe it
> to myself.
>
> I remember using a BeeHive terminal back in the early 80s. That
also had
> 24 lines
> with an optional 25th status line that you could enable or
disable. I
> think it was used
> to report things like the baud rate, auxillary port status and so
on. I
> think it might have
> had a number of screen pages too.
>
> I'm not sure if 24 lines makes the circular buffer wrap around any
easier.
> I don't think you need a barrel shifter to offset the character
rows,
> just an offset on the row counter. Thats what I have done but when
> the offset register gets to large or wraps around to zero, the
offset
> calculation
> goes wrong and you get some modulo counter offset. I've just got
to look
> a little closer at how I've done offset.
>
> Also, I need a better character generator. Characters are 8 pixels
x 8pixels
> and I have two scan lines per character row which does not leave
much space
> between characters on different rows. It would be nice to have an
8 x 12
> pixel
> character generator, but then the ROM would double in size, which
may be
> a problem for the Spartan 2 board.
>
> John.





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Re: Re: Simple Character CRT Core Needed - John Kent - Sep 9 22:21:00 2004

Hi Richard ....

I think I've got the bugs out of the VDU ...

It's up on my web page.

http://members.optushome.com.au/jekent/Spartan3/index.html

Don't forget to refresh your browser.

The Character generator ROM still needs a bit of work.

John.

--
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Re: Simple Character CRT Core Needed - rtstofer - Sep 10 9:28:00 2004


I grabbed it this morning - I'll be playing with it over the
weekend. The shower always worked for me as well. Maybe someone
should study that - give up cubes and install showers. Lighten up
the office. Well, except I'm retired - no office.

--- In , John Kent <jekent@o...> wrote:
> Hi Richard ....
>
> I think I've got the bugs out of the VDU ...
>
> It's up on my web page.
>
> http://members.optushome.com.au/jekent/Spartan3/index.html
>
> Don't forget to refresh your browser.
>
> The Character generator ROM still needs a bit of work.
>
> John.
>
> --
> http://members.optushome.com.au/jekent




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Re: Re: Simple Character CRT Core Needed - John Kent - Sep 10 10:58:00 2004

I should have been in my cubical but I was up until the early hours of
the morning fixing my HP5L laser printer trying to work out how to
install a new pick up roller. I work fairly flexible hours (part time).
Bad arthritis has left me with bionic joints and a rather lazy work ethic.

I've been looking around for a 7 x 9 or 7 x 13 character generator that
looks a
bit better than what I have at the moment but I could not find much on
the web.
I think the one I'm using is pinched from a Comodore 64, but I must have
been
out by a row when I spliced it together because I had to fiddle it a bit
to get
number and characters to line up on the bottom line.

John.

rtstofer wrote:

>I grabbed it this morning - I'll be playing with it over the
>weekend. The shower always worked for me as well. Maybe someone
>should study that - give up cubes and install showers. Lighten up
>the office. Well, except I'm retired - no office. --
http://members.optushome.com.au/jekent




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Re: Simple Character CRT Core Needed - rtstofer - Sep 10 13:35:00 2004


Sydney is about 151 degrees East and San Francisco is about 122
degrees West so we're about 273 degrees apart - figure 3/4 of a day
or 18 hours ignoring local offsets for daylight savings time. Too
much time studying celestial navigation...

I still have a couple of issues: First, my generic 82 key keyboard
doesn't work at all with the PS/2 port although it works on my Dell
computer. Don't know what that's about. My Dell 101 key keyboard
works at +5V but I get double strokes (press/release) which is what
the keyboard sends.

I also think I still see times when the counter problem reappears.
If I enter an invalid (WHAT?) command and then press Enter
repeatedly, as the screen scrolls it displays that odd line position
as before but higher on the screen. I usually see it in the upper 4
lines, give or take.

I was going to rebuild the project but, as you are up anyway, I
thought I would send this along. --- In , John Kent <jekent@o...> wrote:
> I should have been in my cubical but I was up until the early
hours of
> the morning fixing my HP5L laser printer trying to work out how to
> install a new pick up roller. I work fairly flexible hours (part
time).
> Bad arthritis has left me with bionic joints and a rather lazy
work ethic.
>
> I've been looking around for a 7 x 9 or 7 x 13 character generator
that
> looks a
> bit better than what I have at the moment but I could not find
much on
> the web.
> I think the one I'm using is pinched from a Comodore 64, but I
must have
> been
> out by a row when I spliced it together because I had to fiddle it
a bit
> to get
> number and characters to line up on the bottom line.
>
> John.
>
> rtstofer wrote:
>
> >I grabbed it this morning - I'll be playing with it over the
> >weekend. The shower always worked for me as well. Maybe someone
> >should study that - give up cubes and install showers. Lighten
up
> >the office. Well, except I'm retired - no office.
> >
> >
> --
> http://members.optushome.com.au/jekent




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Re: Re: Simple Character CRT Core Needed - John Kent - Sep 10 22:54:00 2004

I can't reproduce your problem with the display ... but I borrowed a
PS/2 keyboard
and as you say ... it has problems. I've updated the monitor ROM to
filter out key releases
and undefined keys are mapped at $FF rather then $2e ("."). I notice the
keyboard
handles Shifts but not Control. I'll try post my updates soon.

John.

rtstofer wrote:

>Sydney is about 151 degrees East and San Francisco is about 122
>degrees West so we're about 273 degrees apart - figure 3/4 of a day
>or 18 hours ignoring local offsets for daylight savings time. Too
>much time studying celestial navigation...
>
>I still have a couple of issues: First, my generic 82 key keyboard
>doesn't work at all with the PS/2 port although it works on my Dell
>computer. Don't know what that's about. My Dell 101 key keyboard
>works at +5V but I get double strokes (press/release) which is what
>the keyboard sends.
>
>I also think I still see times when the counter problem reappears.
>If I enter an invalid (WHAT?) command and then press Enter
>repeatedly, as the screen scrolls it displays that odd line position
>as before but higher on the screen. I usually see it in the upper 4
>lines, give or take.
>
>I was going to rebuild the project but, as you are up anyway, I
>thought I would send this along. >

--
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