Hi, time to revisit this topic..
I have a 16702b, pimped out (replaced all fans with low noise noctuas, option 003 memory (main and video), scsi to CF card and high speed CF card instead of rotating hdd, and all works well, except the annoying fussiness with mice and keyboards..
So time to investigate further.
Definitely add the 1k pullups, as already discussed.
Here is what I found helped:
Change the 4 data line filter caps near the 6 pin ps/2 mouse/keyboard connectors from 10nF (way too large!) to 1nF.
This will make the ps/2 comms edges and levels good for just about all keyboards and mice.
HOWEVER..
I still had a keyboard (IBM SK-8840, with integrated trackpad and trackpoint) that would not work. Signal levels were good, and other keyboards worked fine.
So, at first I thought it might be the supposed requirement of HP-UX to use a keyboard that supported code set number 3, and I decided to capture the keyboard boot up sequence on my mso-x 4054a
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
Results were surprising.
hst = 16702B logic analyser
kbd = attached keyboard
First, a working keyboard..
(power up)
0xAA (kbd to hst) Keyboard passed BAT (power up) self tests.
0xF5 (hst to kbd) Disable scanning
0xFA (kbd to hst) ACK
0xF2 (hst to kbd) Get Keyboard ID
0xFA (kbd to hst) ACK
0xAB (kbd to hst) Keyboard ID = 0xAB83
0x83 (kbd to hst)
0xFF (hst to kbd) Reset keyboard/perform BAT tests
0xFA (kbd to hst) ACK
0xAA (kbd to hst) Keyboard passed BAT (power up) self tests.
0xF0 (hst to kbd) Set scan code to "scan code set 2" Looks like the scan code 3 stuff was a furphy
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
0xFA (kbd to hst) ACK
0x02 (hst to kbd) 0x02
0xFA (kbd to hst) ACK
0xF0 (hst to kbd) Get current scan code (should equal what we just asked for)
0xFA (kbd to hst) ACK
0x00 (hst to kbd) 0x00 (request scan code)
0xFA (kbd to hst) ACK
0x02 (kbd to hst) 0x02 got what we expected
0xED (hst to kbd) Set LEDs
0xFA (kbd to hst) ACK
0x02 (hst to kbd) Set NUM lock LED on
0xFA (kbd to hst) ACK
0xF4 (hst to kbd) Enable scanning
0xFA (kbd to hst) ACK All done now, working keyboard..
For the non working keyboard, this is what I found..
(power up)
0xAA (kbd to hst) Keyboard passed BAT (power up) self tests.
0xF5 (hst to kbd) Disable scanning
0xFA (kbd to hst) ACK
0xF2 (hst to kbd) Get Keyboard ID
0xFA (kbd to hst) ACK
*** 0xAB (kbd to hst) Keyboard ID = 0xAB84
*** 0x84 (kbd to hst)
AAAnd.. That's all she wrote! No more keyboard comms, no keyboard attached.
So, unless the HP-UX ps/2 keyboard driver sees a keyboard with ID = 0xAB83, it will ignore the attached keyboard.
This should be a fairly easy fix.. Just patch the binary of the ps/2 driver to bypass this ID test.. I will leave this as an exercise for those more skilled than I in such matters
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Cheers,
Pete