18 Apr
2002
18 Apr
'02
7:45 p.m.
From owner-classiccmp(a)classiccmp.org Thu Apr 18
15:17:12 2002
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Date: Thu, 18 Apr 2002 22:38:24 +0100
From: Dave Woodman <dave(a)naffnet.org.uk>
Organization: The Nicely Naff Network
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To: classiccmp(a)classiccmp.org
Subject: QBUS VAX and M7941 under VMS - info needed!
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Sender: owner-classiccmp(a)classiccmp.org
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Hi all,
I have a MicroVAX (BA123 enclosure, KA650 CPU) that I would like
to put to work... to this end I have two M7941 (DRV11) parallel I/O
cards that I would like to bring into service. The Micronotes say that
this card is compatible with the 22-bit QBUS, and I have the Field
Service print set so I can set the CSR and vectors to appropriate
values.
Of course, VMS does not have a driver for these cards, but I am
not too frightened by the prospect of a little code - here lies the
problem! Can anyone tell me just how this card maps into the I/O space,
given the CSR? I would like to know just where to read from and write to
in order the drive the beastie...
It's sort of standard DEC for a parallel interface.
CSR + 2 is the output buffer, connected to connector J1
Bits in CSR+2 are read/write to the CPU
besides the data lines, J1 has some control bits
REQA which maps to CSR<15> and is read-only
NEWDATA, pulse output by CPU writing to CSR+2,
which should be used to clear REQA
CSR1 which is CSR<1>, read-write for device control
CSR + 4 is the input buffer, connected to connector J2
Bits in CSR+4 are read-only to the CPU
J2 has control bits:
REQB mapped to CSR<7>, read-only
DATATRANS, pulse output by CPU reading CSR+4,
should be used to clear REQB
CSR0 which is CSR<0>, read-write for device control
CSR has the usual INT_ENB A at <6> and INT_ENB A at <5>
INT_ENB AND REQ makes an interrupt. Interrupt A at VEC, B at VEC+4.
Information from "microcomputer interfaces handbook 1980"
EB-17723-20
carl
--
carl lowenstein marine physical lab u.c. san diego
clowenstein(a)ucsd.edu