> 
> I think I have some documentation on the "utility chip" (which is
> where the Domain keyboard port lives...)  I'll have to dig it up (it's
> buried in my extremely disorganized pile of misc. hp300 documentation).
> 
> The utility chip implements, among other things, 4 (I think) 16550-like
> UARTs.  One of these UARTs is the domain keyboard port.  (I think the
> utility chip also has the PIC for the optional Strider EISA bus...)
> 

Oh yes, if that really exists, I'd like to see some notes about it. From the
dissassembly of HPUX's apollo_pci.o I can see that there are some infos about
the UARTs:
@(#) PATCH_8.0: apollo_pci.o 55.2 94/08/22 PHKL_4656^
apollo_pciinit: Internal RS-232 not at sc 5/6/9^
CONSOLE is Apollo RS-232 Port at select code %d
Internal RS-232 not at sc 5/6/9
Internal RS-232C Serial Interface
  With 8 byte rcv fifo.
  WARNING: Interface card interrupt level at %d instead of 5.
  This configuration is for HP internal usage only.

So this is at least a stripped-down quad 16550 - if it is a 16550 at all...
Futhermore it looks like the visible 16550 in a 400t is only used in HPUX mode,
whereas in Domain/OS mode all four utility chip UARTs are used. Looks like the
lines between the serial port's first line (i.e. pins 2,3, etc) are switched or
shared between the single 16550, appearing like a DIO board with interrupt
control registers, and the SIO 1 of the quad UART. 

If you have such info, and have some clue about where it lives in address land,
this would be very nice....

>Making it work with the ITE would mean finding all of the assumptions
>of HIL in the console code, and chaning the interface to deal with both
>types... also, the console probe code would have to determine what sort

Interestingly SYS_PBOOT/SYS_NBOOT work even with a RS232, but this has to be
configured in the EEPROM. Furthermore, the behaviour of the Domain keyboard has
to be examined, as it is completely different to the HIL stuff. Perhaps
something similar to a Sun keyboard; I assume that there are different modes
(say, due to compatibility with earlier keyboards) to specify ASCII keys or
up/down transitions. But still, an auto-discover will be a nice thing... and
updating the SCSI stuff, too (like reconnect for tapes, automatic config for
disks appearing after booting, etc).

Thanks, Michael