Aui wrote on 2026-04-15, 06:16:
Thank you ! That diagram is very helpfull. Indeed the XT PSU has one red wire missing. I checked and it is alive. I get some boot screen with XT-Bios... and then some error code #5. Now imediately I have another question - the same "Trick" i.e. using newer AT class harware will not work for the Keyboard right ? So I will either need a real XT class keyboard (I dont have one) or some adapter (I do have an AT Keyboard - with 5pin DIM connector) ? What would be the fastest solution so I can continue testing ?
If there is only 2 instead of 3 RED wires, it should still work. These are in parallel and are multiple to handle higher current needed by some expansion cards.
Unless you have it loaded with a lot fo extras, 2 should be enough.
An XT needs and XT keyboard, the interface changed a bit with the AT... Some third party keyboards of that era has a switch where you could select AT or XT.
IIRC the original XT didn't have visible POST error code, and used a series of beeps - IIRC 5 was something fairly serious and it wouldn't get far enough to show a screen.
It would seem this one has some sort of enhanced POST a showing Error#5 might indicate "bad or missing keyboard"
- also worth confirming that this board doesn't expect an AT type keyboard - it looks like it might have been "improved" from original XT -
- Dave ; https://dunfield.themindfactory.com ; "Daves Old Computers" ; SW dev addict best known:
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