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

[Colin Hinz]

On Wed, 14 Dec 2011, 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.

Indeed, these parts are hella obsolete. Even CEM chips are modern by
comparison....

> So I was wondering if anyone had advice on a relatively easy to get
> RAM chip that isnt too hard to use?

Any RAM chip which is an "asynchronous static RAM" is going to be
reasonably easy to use, and (lo and behold) they're still commonly
available in DIP form and 5V power supply. Jameco has lots of 'em.
The 2016/6116, 6164, and 62256 types are the most common.

For newer technology there's, say, the Cypress CY7C199C, which is
still a 5V TTL-compatible part in a DIP.

> 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.

I learned a lot about digital/computer electronics back in the day,
by reading the various hobbyist magazines which were on the
newsstands back then. BYTE was in many respects the best of the
lot, and you can read many of them by going here:

http://www.atariage.com/forums/topic/167235-byte-magazine/

Happy downloading!

- Colin