[sebhc] memory for the h-8
Watzman at neo.rr.com
Sun Aug 13 20:34:08 CDT 2006
The part you found was probably a variant of the 6116, 2K x 8 "byte wide".
These have compatible pinouts with EPROMs (in this case, a 2716). I know
that there is also a 6164, which is 8K x8; 8 of these will give you a full
64k (but you would have to emulate the H8's "extended configuration card" to
allow both "normal" (e.g. HDOS and monitor ROM) operation, and an all-RAM
configuration for CP/M. There might be a 64K x 8 memory card (one chip for
the entire 64K), but precisely because of the need to support both normal
and extended modes, it might be easier to implement the necessary card with
smaller parts. However, 6116's are plentiful and cheap, I'd think you could
find them for more like $2 each from a surplus dealer (as used pulls, but as
long as they work, who cares).
From: sebhc-bounces at sebhc.org [mailto:sebhc-bounces at sebhc.org] On Behalf Of
davidwallace2000 at comcast.net
Sent: Sunday, August 13, 2006 8:39 PM
To: sebhc at sebhc.org
Subject: Re: [sebhc] memory for the h-8
The bad news is you probably won't find 4044s, or you'll pay collectors'
prices for them.
The good news is that almost any modern static RAM could be adapted to the
H8 bus if you don't insist of trying to make it fit in the WH8-16 card.
It's a matter of making the address decoding work and buffering the address,
data and control lines to the RAM -- and the schematic of the WH8-16 will
show you how to do that.
Most anything you could buy would be faster than needed (which is not
harmful) and you'd probably wind up with one card that fully populates the
H8's address space.
Example: I found a 2K x 8 SRAM part with 250 ns access time at DigiKey for
$4.28 (each). It's a 24-pin DIP (5V VCC) and appears at a cursory glance to
be compatible with the requirements. An octal decoder and some buffers and
eight of these chips would make a 16K memory board in probably half a card's
worth of space. The chip cost would be under $50.
-------------- Original message --------------
From: WVerish at aol.com
I have a 16 k static RAM memory board that came with my
H-8, but it is un-populated. The chips required for it are TMS4044 chipsThey
are 4096 by 1 bit. The computer currently has only 8K of static RAM
installed. This makes it very hard to write any real BASIC programs due to
the lack of string handling capability with only B.H. BASIC instead of
extended B.H. BASIC. I know that my 16K board could probably work with other
chips, but due to their cost I really can't afford to make a mistake. Any
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