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A quite rare expansion unit belonging to the "sidecar" class, where several interesting ideas have been realized. Unfortunately, I don't have this item on my workbench physically at the moment, but already a view on the PCB promises some nice surprises. For sure the DSR will be read from the EPROM and then be disassembled, but since chances are extremely low to get hold of my own unit, it will flay back to the states afterwards. The company Axiom produced several variants of this interface for different computers, all carrying the prefix "Parallax" - currently I only know about one for IBM-PC named "Parallax468". However, this is irrelevant for our analysis - so here you have the manual. | |||||||||||||||||||||
The Hardware | |||||||||||||||||||||
This are the integrated circuits you can find on the board (1 each):
There are four jumpers on the PCB, one of which allows the board to be powered by the printer (!). Three more have an impact on the DSR: for compatibility with old SW modules that only know about RS232, the card can also be addressed with RS232 (optionally plus /1, /2) instead of PIO (which is actually wrong, since a readback is not provided) or AXIOM (J1), and the CRU address can be changed to >1E00 (J2+J3) instead of >1B00 - all quite martial by separating conductors and soldering new bridges... More to come in March 2026 - stay tuned! |
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All pictures on this very page were made by Jan H. Should you find them elsewhere, they're stolen from here! |
Last updated: 2025-10-23 CW |