26 Jan
2009
26 Jan
'09
10:45 p.m.
Hey all --
Acquired an IMSAI 8080 in half-assembled condition (but the price was
right). I believe that (after doing some thorough cleaning, debugging,
and replacing of old cabling) that I've got the front panel and CPU
functioning correctly. However, the IMSAI came without any RAM cards so
I'm unable to go any further at the moment.
I have one S-100 RAM card but I have no documentation on it and it's
missing a couple of ICs (and what they're supposed to be, I don't
know). It's a PSS RAM65. My internet searches for info confirm that
the card does indeed exist, but I can find no technical information.
From my research, my understanding is that S-100 RAM cards are fickle
and compatibility with front-panel machines can be an issue. Does
anyone have any recommendations for what to look out for as I begin my
search? Anyone have any decent RAM cards they'd be willing to part with?
Thanks!
Josh
27 Jan
27 Jan
6:24 a.m.
----------------------------------------
Date: Mon, 26 Jan 2009 22:45:33 -0800
From: derschjo at mail.msu.edu
To:
Subject: Recommendations for IMSAI-compatible RAM cards?
Hey all --
Acquired an IMSAI 8080 in half-assembled condition (but the price was
right). I believe that (after doing some thorough cleaning, debugging,
and replacing of old cabling) that I've got the front panel and CPU
functioning correctly. However, the IMSAI came without any RAM cards so
I'm unable to go any further at the moment.
I have one S-100 RAM card but I have no documentation on it and it's
missing a couple of ICs (and what they're supposed to be, I don't
know). It's a PSS RAM65. My internet searches for info confirm that
the card does indeed exist, but I can find no technical information.
From my research, my understanding is that S-100 RAM cards are fickle
and compatibility with front-panel machines can be an issue. Does
anyone have any recommendations for what to look out for as I begin my
search? Anyone have any decent RAM cards they'd be willing to part with?
Thanks!
Josh
Hi Josh
If it is static RAM you should be able to make it work.
Don't even try with DRAM. You'd be luck to get them working
on a IMSAI. Most DRAM needs a running processor. If
you stop the processor you lose the data. Some do have
circuits to keep refresh going but these are only
the rarer early ones specifically designed for a
front panel machine.
Have you done any tracing of the circuit. I had a card
once with a couple missing parts that I'd had sitting around
for a few years that I wanted to use. It was missing a
few parts as well. After tracing the circuit, I found
that the missing parts were for bank selection and were
not needed for normal use.
Static RAMs have relatively simple circuits. Just
trace things out. ?The missing chips should be easy
to determine.
Dwight
_________________________________________________________________
Windows Live? Hotmail?:?more than just e-mail.
http://windowslive.com/explore?ocid=TXT_TAGLM_WL_t2_hm_justgotbetter_explor…
8:41 a.m.
The Compupro RAM series (RAM16, etc.) do a good job for me.
-----Original Message-----
From: cctalk-bounces at classiccmp.org
[mailto:cctalk-bounces at classiccmp.org]On Behalf Of Josh Dersch
Sent: Tuesday, January 27, 2009 1:46 AM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Recommendations for IMSAI-compatible RAM cards?
Hey all --
Acquired an IMSAI 8080 in half-assembled condition (but the price was
right). I believe that (after doing some thorough cleaning, debugging,
and replacing of old cabling) that I've got the front panel and CPU
functioning correctly. However, the IMSAI came without any RAM cards so
I'm unable to go any further at the moment.
I have one S-100 RAM card but I have no documentation on it and it's
missing a couple of ICs (and what they're supposed to be, I don't
know). It's a PSS RAM65. My internet searches for info confirm that
the card does indeed exist, but I can find no technical information.
From my research, my understanding is that S-100 RAM cards are fickle
and compatibility with front-panel machines can be an issue. Does
anyone have any recommendations for what to look out for as I begin my
search? Anyone have any decent RAM cards they'd be willing to part with?
Thanks!
Josh
No virus found in this incoming message.
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1/26/2009 6:37 PM
1:01 p.m.
Depends on how "vintage" you want to be and the speed of your CPU.
For a couple of years, I used the SSM 8K SRAM boards (64 x 21L02)--
but that was on a 2MHz Z80. Later, I used a 64K DRAM board (Digital
Research: Computers, I think) that used 4116s and worked all right.
What I would not recommend is the early DRAM boards (e.g., the MITS
4K boards). They can be very flakey, even when when they were new.
If in doubt, stick with SRAM--fewer timing issues.
As another poster has noted, the CompuPro boards were good.
Cheers,
Chuck
2:34 p.m.
Would it be that hard to create a new board that used a single 64K SRAM?
g.
--
Proud owner of F-15C 80-0007
http://www.f15sim.com - The only one of its kind.
3:09 p.m.
On 27 Jan 2009 at 14:34, Gene Buckle wrote:
Would it be that hard to create a new board that used
a single 64K SRAM?
Not at all--just a little TTL "glue" (or maybe a single CPLD) should
do the trick. Heck, you could use a 512K SRAM and add logic for bank
switching and still have most of the board left over.
Cheers,
Chuck
28 Jan
28 Jan
8:27 a.m.
On Tuesday 27 January 2009 05:34:30 pm Gene Buckle wrote:
Would it be that hard to create a new board that used
a single 64K SRAM?
g.
I have a prototyping board or two around and was thinking along the lines of
such an application. With the chips available thse days I suspect I'd
probably want to put a lot more than just 64K on it, though.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
27 Jan
27 Jan
6:38 p.m.
Chuck Guzis wrote:
Depends on how "vintage" you want to be and
the speed of your CPU.
For a couple of years, I used the SSM 8K SRAM boards (64 x 21L02)--
but that was on a 2MHz Z80. Later, I used a 64K DRAM board (Digital
Research: Computers, I think) that used 4116s and worked all right.
What I would not recommend is the early DRAM boards (e.g., the MITS
4K boards). They can be very flakey, even when when they were new.
If in doubt, stick with SRAM--fewer timing issues.
As another poster has noted, the CompuPro boards were good.
Godbout static ram cards work great in my Imsai.
Any cards which uses the 6116 static rams work fine too.
My SOL20 16K dram cards work fine in mine too.
=Dan
[ = http://www2.applegate.org/~ragooman/ ]
29 Jan
29 Jan
12:04 a.m.
Thanks everyone for all the suggestions and advice. I'll keep my eyes
peeled for some good SRAM cards (a few people on the list have offered,
so I'm off to a good start!).
Thanks again!
Josh
Chuck Guzis wrote:
Depends on how "vintage" you want to be and
the speed of your CPU.
For a couple of years, I used the SSM 8K SRAM boards (64 x 21L02)--
but that was on a 2MHz Z80. Later, I used a 64K DRAM board (Digital
Research: Computers, I think) that used 4116s and worked all right.
What I would not recommend is the early DRAM boards (e.g., the MITS
4K boards). They can be very flakey, even when when they were new.
If in doubt, stick with SRAM--fewer timing issues.
As another poster has noted, the CompuPro boards were good.
Cheers,
Chuck
27 Jan
27 Jan
3:48 p.m.
On 1/27/09 11:41 AM, "Bill Sudbrink" <wh.sudbrink at verizon.net> wrote:
The Compupro RAM series (RAM16, etc.) do a good job
for me.
I agree with this. Over the years, I've collected and replaced my various 8k
and 16k cards with all CompuPro RAM16 or RAM17 cards. I've had other good
and reliable cards, SSM and Vandenberg cards, but they all use odd and hard
to replace RAM chips.
The thing I like about the RAM16 and RAM17 is that they use 6116 SRAM chips
which are pin-compatible with 2716 EPROMS. So, the board can double as an
EPROM board. This is what I have in my IMSAI.
Rich
--
Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator
http://www.altair32.com
http://www.classiccmp.org/cini
12:46 p.m.
Mine runs just fine with Cromemco memory (16K, 64K).
I'm in the midst of moving my workshop and a whole bunch of other tasks, but in a
couple of months I can look through my box of cards and see what I have in excess.
But time isn't available right now.
Regards,
Vern
--- On Mon, 1/26/09, Josh Dersch <derschjo at mail.msu.edu> wrote:
From: Josh Dersch <derschjo at mail.msu.edu>
Subject: Recommendations for IMSAI-compatible RAM cards?
To: "On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
Date: Monday, January 26, 2009, 10:45 PM
Hey all --
Acquired an IMSAI 8080 in half-assembled condition (but the
price was right). I believe that (after doing some thorough
cleaning, debugging, and replacing of old cabling) that
I've got the front panel and CPU functioning correctly.
However, the IMSAI came without any RAM cards so I'm
unable to go any further at the moment.
I have one S-100 RAM card but I have no documentation on it
and it's missing a couple of ICs (and what they're
supposed to be, I don't know). It's a PSS RAM65.
My internet searches for info confirm that the card does
indeed exist, but I can find no technical information.
From my research, my understanding is that S-100 RAM cards
are fickle and compatibility with front-panel machines can
be an issue. Does anyone have any recommendations for what
to look out for as I begin my search? Anyone have any
decent RAM cards they'd be willing to part with?
Thanks!
Josh
5758
days inactive
5760
days old
10 comments
9 participants
participants (9)
-
cclist＠sydex.com -
derschjo＠mail.msu.edu -
dkelvey＠hotmail.com -
geneb＠deltasoft.com -
ragooman＠comcast.net -
rcini＠optonline.net -
rtellason＠verizon.net -
vern4wright＠yahoo.com -
wh.sudbrink＠verizon.net