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Gary Kaufman's IMSAI MPU-A Reproduction Board

glitch

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Some of you have probably heard mumblings online about how someone's doing an IMSAI MPU-A reproduction. Behold:



Gary Kaufman had a blank IMSAI MPU-A scanned and did a prototype run of boards. This is the same scanning technique that we've used on the OSI reproduction boards and my SSM IO-2 reproduction. I tweaked the Gerber files for him and added info regarding the design's status as a reproduction. Gary will be selling production-run blank boards soonish at around $30-40 per board depending on final costs. The boards will be run with hard gold edge plating (the prototype above is HASL, of course). I'll be building up a few parts kits for these boards.

Intel 8216 bus buffers replaced with their Soviet clone counterpart:



Running in my IMSAI:



You can see garbage from the Polymorphic VTI on the little monitor; it hasn't been initialized yet. I dropped in a ROM board with the Vector Graphic ROM monitor with VTI drivers:



It lives! Full album here: https://imgur.com/a/tAepr
 
There will be parts kits available for both, as well. Just got in an order of correct Thermalloy heat sinks!
 
Board are in production, and I'll offer them up in a few weeks.

I also have Altair 8080 CPU boards being fabricated.

Several folks including Glitch have been a huge help in making this possible.

- Gary

Did you do a prototype run of the Altair CPU too? If so has Glitch and/or others tested a prototype of the Altair CPU?

When orders are taken I'll commit to three (3) each of the Imsai and Altair CPU boards and parts kits for all.

- Jeff
 
Just waiting to figure my final costs, but will be in the $30 - $40 each range for bare boards. About 1/2 the cost will be going to cover the purchase/borrowing of the bare boards, scanning and prototype production/shipping.

I should be ready to offer boards in about 2 weeks.

- Gary
 
The Altair CPU board has been corrected from "CPU BB" to "CPU BD" in the final production Gerbers :p

Super excited to have reproduction boards actually *available* to us hobbyists at a fair price. I believe Gary is running them full-spec with hard gold plating and all, so they should also be very *durable* reproductions. Drives me nuts to see more expensive boards with HASL or ENIG on an edge connector!
 
I thought that was on purpose because they are so close :) It is an excellent reproduction.

It says it's a reproduction on the back, with Gary's site's URL. They do look nearly identical to the originals from the front, especially the IMSAI board!
 
Well done Gary. This is excellent.

I'd like to register my interest for 2 x kits (including 2 x PCBs), when available.

Are you able to post a few notes documenting the steps taken (tools used etc) to get from a scan of the old board, to a clean set of Gerbers and drill file? I recently finished an unrelated reproduction project. It took several hundred hours to accurately measure the placement of tracks and vias, while redrawing the lot in KiCAD. I'd say I did it in about the least efficient way possible!

Malcolm.
 
You send the boards to Mile High Test/Gardien Services, pay the fee, and get Gerbers back. They'll digitize all of the layers you'd like (silkscreen, solder mask, etc.). A two-layer S-100 sized board costs around $250. The board has to be stripped of all components. They can do multilayer (4+ layer) boards, but the board is destroyed in the process. Well worth the cost IMO -- as you discovered, there's a *lot* of time in it, and I wouldn't be able to get nearly as much done if I were doing the conversion to Gerbers myself.
 
IMSAI and Altair CPU Boards are now available, please see the posting in the marketplace for-sale section.

Repro_Front_s.jpg


http://www.vcfed.org/forum/forumdisplay.php?28-Vintage-Computer-Items-For-Sale-or-Trade
 
6/6/2018

SUBJECT- IMSAI 8080 PARTS LIST

If anyone has purchased one of Gary Kaufman's IMSAI 8080 reproduction boards and is in need of a parts list, I have enclosed one if it would be useful to anyone.

> Charles

IMSAI_8080_Model.jpg
Parts.jpg
View attachment IMSAI_Parts.zip

6/6/18

UPDATE-
Just an Update to the parts list. As I am currently building the board I noticed the 1/2 watt resistors are really too big to fit
when mounted side by side as in R25-R32, R12-R11, and R8-R7. It would be better to use 1/4 watt resistors throughout.
You might try...

( 1) 291-470-RC
(19) 291-1K-RC
(10) 291-4.7K-RC

These are still carbon film brown body resistors.

>Charles
 
Last edited:
Thanks for the list, Dawsoca. I hope to building one of these soon.

Is there any reason NOT to use 1/4 watt resistors throughout as Charles mentions above? Half-watt seems kinda overkill.

<*> Jim
 
The resistor used in the zener regulated supply (the 470R) probably needs to be 1/2W. The rest can be 1/4W.
 
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