Michael Joosten <joost@ori.cadlab.de>  wrote:
 > some Ex-HP guy working at Cayman (Carl Heinzl <carl@Cayman.COM>) gave some
 > infos about the inner workings of the dual mode boot proms, but that's now 3.5
 > years ago.

Do you still have this information?

 > keyboards together, clamping probes to reveal how the protocol works
 > (especially the raw keystrokes + mouse movements). And I'm still interested in
 > having this hp400 working with Domain/OS keyboard, NetBSD *and* an X server!

I'm not sure about mouse movements but in regular mode, the keyboard just
sends ascii at 1200,e,7,1... So, press "A" and you get a 0x41.