Trade Massbuss for LP card?

From: Pat Barron <>
Date: Thu Dec 16 08:57:22 1999

On Wed, 15 Dec 1999, John Lawson wrote:
> In the 11/44 system which is now occupying my evenings... there
> are three Massbuss adaptors [M5904]. I actually have an RA90+power
> supply out in the garage, condition unknown at this time.. I don't
> know anything at all about the Massbuss and it's peripherals, save
> that its serial and kinda fast.

The RH11 UNIBUS MASSBUS adapter actually consists of several boards:

     M5903 MASSBUS terminal tranceiver
     M5904 MASSBUS control tranceiver
     M7294 MASSBUS data buffer and control
     M7294-YA Modified M7294 for RH11-C (used on DECSYSTEM-2020)
     M7295 MASSBUS bus control (RH11-A only)
     M7295-YA Modified M7295 for RH11-B
     M7296 MASSBUS control and status registers
     M7297 MASSBUS parity control

The appropriate boards live in their own section of backplane.

(Does anyone know what the reason is behind Digital putting a "-YA" suffix
on the module number of a board that's been modified somehow? Does it
stand for "Yet Another"...? :-) )

The RA90 is an MSCP drive; you need a UDA50 to run it. MASSBUS drives are
drives like the RP04/5/6 (washing-machine looking), and RM02/03/04/80 (not
quite washing-machine size, but still pretty big). The RP07 is also a
MASSBUS drive, but I am not sure if it will run off of an RH11 (I think
it was originally meant to be attached to an RH20 interface on a
DECsystem-10 or DECSYSTEM-20).

Received on Thu Dec 16 1999 - 08:57:22 GMT

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