@diyelectromusic@mastodon.social
Post #1974725
2026-05-03 14:15 UTC
Ok, can someone tell me either I'm not going crazy and the schematic doesn't match the board, or what obvious thing I'm missing...
https://www.cpcwiki.eu/index.php/PDS_development_system
Look at the schematic and board diagrams for the remade PC card.
The schematic shows D0-3 on the two connectors going to different 244 ICs.
But I'm pretty sure the board shows D0-3 on both connectors linked and going to the same 244.
Look at pin 11 for three 244s...
Replies (1)
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@diyelectromusic@mastodon.social 2026-05-03 15:21
Ok, so finding a printable version of the PCB and overlaying it on a lightbox gives the attached. This seems pretty clear to me that not only are (what I know as) D0 on both 16-way connectors connected, but they are also both connected to input side 2A1 and output side 1Y4 of the same 74LS244. I think I have to at this point conclude that the schematic is wrong...