On Thu, 02 Jun 2005 14:21:32 -0700, Jim Stewart <jstewart@jkmicro.com>
wrote:

>Eric wrote:
>
>> A $1.00 CPLD from Xilinx or Altera would do the job. You would just
>> have to code up a little VHDL or Verilog to define the dual port ram
>> function.
>
>I predict he'll need a macrocell per bit
>and it will cost him more like $3 per part.

If one side supports DMA and other supports a wait operation
you can just use the CPLD to provide a state machine and
buffering: steal from the existing RAM on one side.

Stephen

--
Stephen Pelc, stephenXXX@INVALID.mpeltd.demon.co.uk
MicroProcessor Engineering Ltd - More Real, Less Time
133 Hill Lane, Southampton SO15 5AF, England
tel: +44 (0)23 8063 1441, fax: +44 (0)23 8033 9691
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Another option (if they are still in the catalog):  Motorola MC68HC34.
We used to use them by the hundreds of thousands as dual port rams.
Worked quite well.

On 5 Jun 2005 02:58:28 -0700, cbarn24050@aol.com wrote:

>If your can tolerate slow access times you can program a small micro.
Depends on how you define slow - I'd guess a Ubicom (formerly Scenix) SX chip running at 75MHz could
probably do the job at system speeds of up to about 10MHz 

If your can tolerate slow access times you can program a small micro.

Bad suggestion below, sorry. I missed "dual port".

Hul

Hul Tytus <ht@panix.com> wrote:
> Take a look at the various cmos clocks. Many of these have some ram 
> included.

> Hul

> Davor.S <davor.s@iname.com> wrote:
> > I am looking for a small low cost asynchronous dual port RAM.
> > Cypress and IDT devices are too big and expensive.
> > Is there anything smaller/cheaper? I need only 128 bits (16x8).

> > Best regards

"Davor.S" <davor.s@iname.com> skrev i meddelandet 
news:d7nnn6$b72$1@sunce.iskon.hr...
>I am looking for a small low cost asynchronous dual port RAM.
> Cypress and IDT devices are too big and expensive.
> Is there anything smaller/cheaper? I need only 128 bits (16x8).
>
> Best regards
>

The soon to be available AT94K05AX will give you six 32 x 8 DPRAM,
and an AVR microcontroller in 8 x 8 mm.
There is already silicon on the AT94K10AX which gives you more
and is more expensive.

-- 
Best Regards,
Ulf Samuelsson
This is intended to be my personal opinion which may,
or may bot be shared by my employer Atmel Nordic AB

Take a look at the various cmos clocks. Many of these have some ram 
included.

Hul

Davor.S <davor.s@iname.com> wrote:
> I am looking for a small low cost asynchronous dual port RAM.
> Cypress and IDT devices are too big and expensive.
> Is there anything smaller/cheaper? I need only 128 bits (16x8).

> Best regards

Davor.S wrote:
> I am looking for a small low cost asynchronous dual port RAM.
> Cypress and IDT devices are too big and expensive.
> Is there anything smaller/cheaper? I need only 128 bits (16x8).
> 
> Best regards

  That is a hole in the market.

  There are smaller sized Dualports, but they tend to be old, and
priced like 2716 EPROMS :)
  Dallas used to have a 4 port serial memory, and they still have
a 2404 serial Dual port, and  DS1609 is parallel dual port, but
that is tagged not for new designs, tho you can still buy them...

  Alternatives would be CPLD, but that would use many macrocells,
small FPGA, or maybe you could adapt to use a couple of HCMOS FIFOs - 
those are still active devices ?

-jg

On Thursday, in article <d7nnn6$b72$1@sunce.iskon.hr>
     davor.s@iname.com "Davor.S" wrote:

>I am looking for a small low cost asynchronous dual port RAM.
>Cypress and IDT devices are too big and expensive.
>Is there anything smaller/cheaper? I need only 128 bits (16x8).

Code it into a PLD/FPGA, Altera and Xilinx have standard logic cells
for dual port RAM, just get one with enough D types or memory bits.

All depends on how fast an access speed and size of package is actually
'small' that you need. Let alone 5V or 3V3, power budget and cost.

If you can find an equivalent part for the National 74F410, you could
use smaller PLD to do the dual porting of two devices giving you 16 x 8
RAM/register file from two 16 x 4 devices.

There seem to be several suppliers of the 4 x 4 register file 74HC670 series.
This would need four devices.

Buying small size memory for LUTs and similar is getting more difficult.

If the data is loaded once (or infrequently) but read from both sides, you
could pipeline the data into a Logic Devices L29C525 and hold the data
for reading.

As we don't what you are trying to dual port an what for these are only
outline suggestions I would give at this stage.

-- 
Paul Carpenter          | paul@pcserviceselectronics.co.uk
<http://www.pcserviceselectronics.co.uk/>    PC Services
<http://www.gnuh8.org.uk/>              GNU H8 & mailing list info
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Eric wrote:

> A $1.00 CPLD from Xilinx or Altera would do the job. You would just
> have to code up a little VHDL or Verilog to define the dual port ram
> function.

I predict he'll need a macrocell per bit
and it will cost him more like $3 per part.

It will still be the best solution though.