ckw@hpcupt1.HP.COM (Chick Webb) (06/14/88)
>Subject: HP9000 Series 800 and serial I/O
re: "Can anyone out there especially someone from HP explain why for the
new 825 you can only use the 6-Chan Mux card for communications to ttys
and not the 8-Chan Mux."
The 27130A/B 8MUX (and 27128A ASI) card are very different from the 27140A
(aka 98196A) 6MUX at the CIO backplane.
The CIO 8-port MUX (and ASI, though not asked about) are ROM-based
cards. While sufficient to work adequately on the s500, the ROM
code is not flexible enough to support such extensions as the
SUSP (control Z) character used for job control. Thus not only
a new driver, but also probably new ROMs would be needed to support
these cards. The 6MUX is RAM-based.
It might not be possible to implement such a driver, or, it might have nasty
performance/loading consequences on the 800. As I recall, the 8MUX/ASI
cards interrupt the host and the 6MUX is polled.
We may eventually get a higher port-count MUX on the 800.
(Thanks to a number of folks inside HP for the information contained in
this response.)
Chick Webb "I am sitting in the smallest room of
Hewlett-Packard Company the house. I have your letter in front
Cupertino, CA of me. It will soon be behind me."
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