[sdiy] transistion from 7489/74189 to more modern ram??

Paul Maddox yo at VacoLoco.net
Wed Dec 14 22:12:45 CET 2011


Dan,

 I've got a bunch of 74219s if you're after some? I'm happy to accept offers.

 As for standard SRAM, you really need a CPU... they're all slightly different, but mostly you have a Read/Write pin and an output enable pin.

  to read, you usually bring the R/W pin high, put the address on the bus, the enable the "output enable" by bring it low and read the data out.

 To write, ensure output enable is high (disabled), put address onto bus, put your data onto the data bus, and bring the R/W pin low for short period.

 Best guide is a datasheet to be honest, I've got a stack of older DIL SRAMs if you want (16K and 64K IIRC).

Paul

______________________________________
VacoLoco

http://VacoLoco.net

On 14 Dec 2011, at 20:56, dan snazelle wrote:

> I have bumped into a few projects recently that implement TTL RAM. 
> these RAM chips are extremely straight forward compared to later RAMS i have seen.
> 
> however, they are RARE and expensive.
> 
> So I was wondering if anyone had advice on a relatively easy to get RAM chip that isnt too hard to use?
> 
> also...if anyone knows of a book out there that has a more in depth study of RAM and how to use it than the CMOS cookbook, I would be grateful.
> 
> thanks!
> 
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