Why and when flash memory is needed in embedded system?

On Fri, 22 Sep 2006 10:50:38 +0200, David Brown
<david@westcontrol.removethisbit.com> wrote:

>Some of the old mainframes had absolutely no ROM.  When you boot them, 
>you have to code in the machine code instructions using a set of DIP 
>switches until you've got enough to start booting (from disk, tape, 
>punch card, or whatever).  Fortunately, these things were seldom 
>switched off.

Why would you need any special ROM for the boot loader in any computer
prior to about 1975 ? These old computers had core memory, so there
was not a problem switching these off, they would just continue from
where the power was lost, after the power was restored.

Thus the boot loader code would also remain in memory during a power
failure. Only if some accidently overwrote the boot loader code, it
would have to be entered manually with the front panel toggle switches
(perhaps 10-20 instructions), so that the disk driver could be loaded
from a paper tape. 

To avoid the accidental overwriting of the boot code, some computers
had some circuitry to prevent accidental overwriting the address range
where the boot code was by programs gone mad, but unfortunately, this
did not always work and you had to enter the boot loader manually :-).
 
Paul

On Thu, 21 Sep 2006 13:51:49 -0500, msg <msg@_cybertheque.org_> wrote:
> Tom Lucas wrote:
> 
> ????? wrote:
>> 
>> Speaking to a very old hairy-eared engineered once he told be that the 
>> ROM he used many many years ago was windings of copper wire with ferrite 
>> beads on them to represent data. Apparently they always used women to 
>> wind the wires because they were more accurate than men. But I 
>> digress....
> 
> Holy cow, it wasn't THAT long ago; I did a lot of transformer ROM
> re-wiring (to change code).  --Still have devices running using
> transformer ROM.
> 
> Most transformer ROM used U-cores so that the assembly can be easily
> opened for maintenance (rather than torroids).

At least one of the IBM S/360 series (I _think_ it may have been the
Model 40) had its field-upgradable instruction-set-defining microcode
stored in "transformer-based" ROM known as "TROS" (transformer
read-only storage). The "windings" were conductive patterns embedded
in a plastic strip with square holes for the cores; Engineering
Changes could be done on-site using a small leatherpunch-like tool
to "cut through" some of these traces and leave others intact.

IIRC the Model 30 used CCROS (capacitive) which used a grid of
conductive pads on a plastic sheet the same size and layout as the
standard 80-column punch card. _These_ could be programmed using...
(you guessed it!) the IBM 026/029 keypunch. Since an 80-column card
had 12 rows of holes (960 bits), and since (IIRC) there were only
1/4 as many CCROS pads, that's 240 bits/card; this on a plastic card
that occupied roughly the same volume as 2 CF cards (16Gb by now?).

By the time the S/370s came along (and IIRC some of the later S/360s)
IBM had moved on to 8"-floppy loadable microcode (160,000 bytes!!).

We've come a long way, in this area, at least. <grin>


Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)
--
   "Progress, far from consisting in change, depends on retentiveness-- 
    when experience is not retained, as among savages, infancy is 
    perpetual.  Those who cannot remember the past are condemned to 
    repeat it....This is the condition of children and barbarians, in 
    whom instinct has learned nothing from experience.
                        -- George Santayana, Life Of Reason (1905)
--

"larwe" <zwsdotcom@gmail.com> wrote in message 
news:1158930293.401761.176280@m73g2000cwd.googlegroups.com...
>
> Tom Lucas wrote:
>
>> > What is a GP2X?
>>
>> That wiki that Isaac posted a link for will tell you the facts. In my
>> opinion it is both a good product and a good idea - basically a linux
>> based open source PSP with a major appeal to retro gamers due to the
>> wide variety of emulators available.
>
> Right, I knew of the GP32 but don't really follow it which is why I
> never heard of the GP2X.
>
> It's pretty nifty. The price is good, too.

The price could be what swings it - it is certainly not a technically 
competent as the PSP but I'm sure it wipes the floor with gameboys and 
DS's.

What is needed is for someone to make it a bit more friendly to people 
who just want to play games and then it could take off in a big way. 
However, I think it needs another iteration of hardware development to 
be a success. I'm not convinced that the board space and power taken up 
by the TV-out circuitry can be justified either.

Of course, the tinkering to make it work brings in another type of fan. 
I wouldn't dream of buying a PSP because I'm not a gamer but something 
that needs to be cajoled and poked into working.... ohboygimmegimmegimme 
:-) 

Tom Lucas wrote:
> "larwe" <zwsdotcom@gmail.com> wrote in message 
> news:1158930293.401761.176280@m73g2000cwd.googlegroups.com...
>> Tom Lucas wrote:
>>
>>>> What is a GP2X?
>>> That wiki that Isaac posted a link for will tell you the facts. In my
>>> opinion it is both a good product and a good idea - basically a linux
>>> based open source PSP with a major appeal to retro gamers due to the
>>> wide variety of emulators available.
>> Right, I knew of the GP32 but don't really follow it which is why I
>> never heard of the GP2X.
>>
>> It's pretty nifty. The price is good, too.
> 
> The price could be what swings it - it is certainly not a technically 
> competent as the PSP but I'm sure it wipes the floor with gameboys and 
> DS's.
> 
> What is needed is for someone to make it a bit more friendly to people 
> who just want to play games and then it could take off in a big way. 
> However, I think it needs another iteration of hardware development to 
> be a success. I'm not convinced that the board space and power taken up 
> by the TV-out circuitry can be justified either.
> 

The TV-out circuitry certainly can't be justified - it is in a format 
unsuitable for many TV's (S-Video), the TV adaptor is expensive and 
uselessly short, meaning you have to buy expensive extension cables, and 
the quality varies from very poor, through black-and-white only, to 
absolutely terrible, depending on the game.

The GP2X itself is a great device, and fun for a hand-held games machine 
(it's popular with the kids, and fine for the odd game of SuperTux). 
But don't even consider the TV Out.

> Of course, the tinkering to make it work brings in another type of fan. 
> I wouldn't dream of buying a PSP because I'm not a gamer but something 
> that needs to be cajoled and poked into working.... ohboygimmegimmegimme 
> :-) 
> 
> 

"David Brown" <david@westcontrol.removethisbit.com> wrote in message 
news:4513e86e$0$2184$8404b019@news.wineasy.se...
> Tom Lucas wrote:
>> "larwe" <zwsdotcom@gmail.com> wrote in message 
>> news:1158930293.401761.176280@m73g2000cwd.googlegroups.com...

>>>>> What is a GP2X?
>>
>> What is needed is for someone to make it a bit more friendly to 
>> people who just want to play games and then it could take off in a 
>> big way. However, I think it needs another iteration of hardware 
>> development to be a success. I'm not convinced that the board space 
>> and power taken up by the TV-out circuitry can be justified either.
>>
>
> The TV-out circuitry certainly can't be justified - it is in a format 
> unsuitable for many TV's (S-Video), the TV adaptor is expensive and 
> uselessly short, meaning you have to buy expensive extension cables, 
> and the quality varies from very poor, through black-and-white only, 
> to absolutely terrible, depending on the game.
>
> The GP2X itself is a great device, and fun for a hand-held games 
> machine (it's popular with the kids, and fine for the odd game of 
> SuperTux). But don't even consider the TV Out.

I wasn't planning on getting the TV-out cable but I definitely won't 
now. The breakout board that Game Park now sell is a great idea and is 
the perfect place to have the TV-out circuitry although VGA would be 
much more sensible.

Whilst I don't game very often, I have found the few I've tried to be 
pretty good, if a little rough round the edges. The emulators are where 
I'm at at the moment but I need to get squidgeSNES to work smoothly on 
mariokart (the release of which, of course, was the greatest event to 
have happened to the earth) before I can concentrate enough to fully 
drown out the girlfriend's yapping.

I wonder whether a wi-fi USB dongle would work on the breakout board? 
Would be nice to be able to stream movies off my server whilst in the 
bath/garden/locked out on the doorstep. 

"larwe" <zwsdotcom@gmail.com> wrote in message 
news:1158930293.401761.176280@m73g2000cwd.googlegroups.com...
>
> Tom Lucas wrote:
>
>> > What is a GP2X?
>>
>> That wiki that Isaac posted a link for will tell you the facts. In my
>> opinion it is both a good product and a good idea - basically a linux
>> based open source PSP with a major appeal to retro gamers due to the
>> wide variety of emulators available.
>
> Right, I knew of the GP32 but don't really follow it which is why I
> never heard of the GP2X.
>
> It's pretty nifty. The price is good, too.

Talking of price, I see your new book is now available in Amazon UK and 
is only &#4294967295;16.49 and has free delivery. You might have made a sale there, 
particularly because I just get paid today and I'm going to be doing 
drunken internet shopping tonight :-) 

Frnak McKenney wrote:
> By the time the S/370s came along (and IIRC some of the later S/360s)
> IBM had moved on to 8"-floppy loadable microcode (160,000 bytes!!).

I always found it amusing that the VAX 11/780 came with a
PDP-11 stuck inside the cabinet.  Not a PDP board, but the
entire computer, case, toggle switches, etc (the VAX itself
had very few blinkenlights on the outside.  The PDP's job was
basically to load the microcode and boot start the VAX, and
it also served as the console.

--
Darin Johnson

Tom Lucas wrote:

> Talking of price, I see your new book is now available in Amazon UK and
> is only =A316.49 and has free delivery. You might have made a sale there,
> particularly because I just get paid today and I'm going to be doing
> drunken internet shopping tonight :-)

Drunken internet shoppers account for at least 80% of my royalties.

When applying for my current job I wanted to bring along a printout of
the amazon.com page for my first book. Luckily I noticed before I
handed it over that the "people who bought this also bought..." section
was full of titles like "How to be a Porn Star", "Find Hookers in Any
City", and blank DVD media.

Tom Lucas wrote:
> "David Brown" <david@westcontrol.removethisbit.com> wrote in message
> news:4513e86e$0$2184$8404b019@news.wineasy.se...
> > Tom Lucas wrote:


> Whilst I don't game very often, I have found the few I've tried to be
> pretty good, if a little rough round the edges. The emulators are where
> I'm at at the moment but I need to get squidgeSNES to work smoothly on
> mariokart (the release of which, of course, was the greatest event to
> have happened to the earth) before I can concentrate enough to fully
> drown out the girlfriend's yapping.

Oh yes Mario Kart, I remember playing that game on ZSNES for DOS on my
Cyrix 6x86 133Mhz. The game has some DSP embedded in the cartridge for
the pseudo 3D. Took a huge performance hit on my 133Mhz. I could barely
hit 30fps on the best of things.

-Isaac

Tom Lucas wrote:
> "Isaac Bosompem" <x86asm@gmail.com> wrote in message
> news:1158857970.781934.86410@k70g2000cwa.googlegroups.com...
> >
> > Tom Lucas wrote:
> >> "larwe" <zwsdotcom@gmail.com> wrote in message
> >> news:1158844321.938326.21960@b28g2000cwb.googlegroups.com...
> >> >
> >> > Tom Lucas wrote:
> >> >
> >> >> > "The answers to your homework can be found in the reading list
> >> >> > provided by your professor".
> >> >>
> >> >> I don't think the students are back yet are they? The UK ones only
> >> >> put
> >> >> down their burger flippers on Sunday and are still too drunk to
> >> >> post
> >> >> on
> >> >
> >> > US students have been back at school for at least two weeks. (My
> >> > wife
> >> > is a seventh grade teacher, and I'm back at college myself... so I
> >> > know
> >> > these things).
> >>
> >> My girlfriend is now in her second week as a newly qualified maths
> >> teacher. Unfortunately, she has little time to do anything else so
> >> all
> >> our conversations must be about what the little buggers have been up
> >> to
> >> this week. I guess this must be revenge for the time I spend
> >> disseminating the virtues of my GP2X to her ;-)
> >
> > You got a GP2X? Cool!
> > I wanted one of those but I decided instead to blow my money on a Palm
> > Zire 71
>
> How is the Zire? Was it the right decision? I'm delighted with my GP2X
> but would like a bit more battery life - it doesn't appear to have any
> power management at all. The chap who did all the power management for
> the Fedora Core distribution is a good buddy so I've been bribing him
> with beer and curries to see if he can put some time into GP2X power
> management. He's back at university now so he should have plenty of time
> available ;-)

How is the battery life on the 2X? I was contemplating purchasing one
maybe.
The Zire 71 is for sure a bit more compact than the GP2X but it doesnt
have nearly as much horsepower or video hardware. I use it as a MP3
player haha, it also has a built in camera, but its resolution is
640x480 so the pics aren't exactly top quality.

It is based on a TI OMAP310 SoC (ARM9 @ 144Mhz). I havent seen any TRUE
3D games on it since I have to pay money for 3D games and I am
certainly not doing that ;).

I just was flipping over the PalmOS v5.x.x documentation. As it so
happens the majority of applications are still compiled for the M68K
derivative that was in the older Palms (VII, V, etc.). For places where
there is a need for performance they can be written in native ARM code
(as "ARMlets") which you can invoke from the M68K code. Tons of example
code and a relatively well documented API. Though the PalmOS Developer
Suite is a ~400MB download :-O!

I admit I am a heavy gamer, so I have both the PSP and the DS Lite. But
neither architecture is as "open" so to speak as the Palm or the GP2X.


> There are 2 ARM9's in use and I believe one is for thinking and the
> other is purely for handling graphics so there should be enough power
> available for a bit of 3D - that would be a very interesting project and
> might be something I could fancy having a crack at.

That'd be neat! If I recall I don't think anything like that has been
made for the GP2X. Mostly high quality 2D games (which are not bad at
all).

> I worked with ARM a good bit so I'm fairly comfortable with the
> processors but I have never coded for Linux before so I have a pretty
> steep learning curve. This is the main reason I bought the GP2X (other
> than for watching the Sopranos on the train) because I think I'll be
> using Linux in my next product and I want to learn how to use it in
> plenty of time. Also once I get the hang of Linux properly then I can
> finally be shot of Windows, for which my patience is dwindling - how
> many iterations of Outlook do they need to get it right?

That seems like a good use for the GP2X. You must have a big SD for the
Sopranos episodes? I like the Sopranos as well. My Zire 71 probably
doesn't have the horsepower to play anything like that buy my PSP for
sure could.

-Isaac