On 10 Apr 2013, at 11:22 AM, <[email protected]> <[email protected]> wrote:
> 2> Assuming that the MASSBUS hardware devices actually supported the extended > configuration, you could certainly add the extra components into the > configuration. The question then becomes do any of the operating systems that > ran on the original hardware support the extended configuration? If the > operation systems don't support the extensions, then adding the extra > simulated components is a waste of time. Otherwise, you just have to ask > yourself "Is it worth the effort?" Note that any new components added to a > simulation should be disabled by default for compatibility with older scripts. RXS-11M-Plus did a very nice job of supporting multiple MASSBUS controllers. Not only that, it supported mixed-MASSBUS configurations -- tapes and disks on the same controller. And, multi-path MASSBUS configurations to dual-port disk drives. Our PDP-11/70 had several MASSBUS disk drives all dual-ported to two MASSBUS controllers. RSX-11M-Plus issued seeks separate from data transfers. Whichever controller was available could be used to issue any command to any drive it could reach. As I recall, the PDP-11/74 could have even more than 4 MASSBUS controllers, because each processor had its own MASSBUS/UNIBUS. Some rather powerful disk configurations could be configured. RSX-11M-Plus had all the code to make it work. (The developers used a PDP-11/74 system.) Larry Baker US Geological Survey 650-329-5608 [email protected]
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