IBM XT 5160 Keyboard issues

[Jules Richardson]

On 12/17/2016 11:14 PM, Devin wrote:
> The machine starts up and runs its memory test, however it gives a 301
> error.

Anything else alongside the 301? If it's a stuck key error then I think the 
firmware spits out the scancode of the offending key (although maybe that 
was only a 5170 and later thing?). Just a 301 on its own would indicate 
something more fundamental.

Check the keyboard cable and connector carefully - I've seen plenty of 
problems with DIN-type connectors on things, and I know that at least one 
of my XT keyboards had damage where the cable goes into the back of the 
keyboard. It may be worth (carefully) taking the keyboard apart to check 
for obvious problems inside, and to check continuity on the keyboard cable 
wires (I think it's a 4-wire setup - power, ground, clock and data - 
although it uses a 5 pin connector with one pin unused)

Check for power at the keyboard socket on the motherboard (I don't have the 
pinouts handy, but I'm sure that google does :-)  and I believe there's a 
PCB-mounted fuse on the system board near to the socket which is worth a look.

cheers

Jules