Massbus - was: Re: VAX 11/750

Christian Gauger-Cosgrove captainkirk359 at
Tue Mar 2 19:27:53 CST 2021

On Thu, 25 Feb 2021 at 21:32, Rich Alderson via cctalk
<cctalk at> wrote:
> As for operating system support, the only DEC operating system which could put
> tapes and disks on the same Massbus was TOPS-20.  Tops-10 explicitly tells you
> in the SYSGEN process that disks and tapes must reside on different channels; I
> believe that ITS follows that same principle.  WAITS, although originally a
> highly divergent offshoot of Tops-10, took the Massbus code from TOPS-20 v5
> when it was ported to a KL-10 at SAIL, so could in theory have disk and tape on
> the same channel.
RSX-11/M+ should as well. It is possible during SYSGEN to define a
"mixed MASSBUS".

Best regards,
Christian M. Gauger-Cosgrove
Contact information available upon request.

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