Delta & XOR S-100 Documentation List

Copyright 2005 by Herbert R Johnson. Last update Aug 31 2005.
Price and other information can be found in this notice.
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Manuals for boards

This company or its products were known as Delta Products, Data Science, US Micro Sales, or XOR Computer. I have the following manuals available:

DP-CPU-B - copy, ask
64K-DQ - copy, ask
DP-DSK - copy, ask
XOR S-100-12 Computer Assembly & operating - copy, ask

Information on Delta Products aka XOR

A customer contacted me in Aug 2005 with information on Delta Products as below. Edits by me are in []'s. - Herb

I run a website for supporting laptops that are becoming "orphans" as their makers abandon the older machines and/or go out of business. But that's not why I'm emailing you today. I got started with S-100 stuff way back when and so I wanted to pass on a few things that I can add to your S-100 databank.

1) Delta Products Corp. was purchased [by U.S. Micro] (or maybe sold most of their inventory to them) at some point in the later days of the S-100 heyday. [US Micro] renamed the Delta Products stuff as XOR and sold a lot of boards for low prices. They may have also changed their at some point to XOR Products or some such name. The XOR line continued for a bit with these S-100 products and then tried to go into the IBM clone business before going out of business. So XOR and Delta Products S-100 boards should be exactly the same stuff, in most cases.

2) Delta/XOR produced a decent S-100 64K Dynamic RAM board that had a weird common failure. The failure was due to the neg. power supply main filter capacitor being soldered into place with reversed polarity. This was for the factory built boards and not just the kit boards. The board was marked with incorrect +/- markings for this cap. and it seems the factory didn't fix this board until way into production, if at all. To prevent this failure or to repair, all that is needed is to pull the old cap. (blown if the board doesn't work) and reverse or replace with a correctly mounted replacement and a reliable board can be had. Capacitor is located in upper corner of board and measuring the voltage from the neg. supply should be -1.5v to ground (I think) when all is correct. Do not assume that the cap is working even if voltage is okay - always replace and observe correct polarity. (Reverse of board markings) [Herb's note: to be certain, trace the lines back to the negative supply and ground to confirm correct polarity.]

3) The Delta Products 5" & 8" Floppy board had a high failure rate (I've got two here now) that seems to be due to poor buffering and or some other design problem. I believe that the main chip set fails and finding replacement Western Digital (I believe?) chip sets may be the death blow for these boards.

Don Burns - President
Orphaned Laptops, LLC

Again, here is how to order S-100 stuff and to email @ me.