aad+@andrew.cmu.EDU (Anthony A. Datri) (08/01/87)
I've seen reference to a board made by Able (ACT) called the Enable/34. While it didn't go into detail, I got the impression that this was a product to give an 11/34 a unibus map and therefore a bigger physical address space. Does anyone know anything more about the nature/availability of such a board? thanks. anthony a datri aad@andrew.cmu.edu
ted@blia.BLI.COM (Ted Marshall) (08/03/87)
I am a former employee of Able. When I worked there (about 5 years ago)
I was involved in modifying RSX-11M to support the Enable/34 so I think
I can give some general information about it. Note: since then I have
not been involved with the PDP-11 line or with Able so I may be
mis-remembering some details. Also, for the same reason, I can't give
you any current information on availability.
The Enable/34 is a box that is cabled to the end of the Unibus on an
18-bit PDP-11 (i.e. the 11/34). The box contains 22-bit memory (all
Unibus memory is removed) and four sets of Unibus Mapping Registers,
each set similar to the UMRs on a 22-bit 11. One set simulated the
22-bit CPU UMRs. Two others (the last was unused as I remember) acted a
PARs for user and kernal mode. With an OS properly modified to
initialize things correctly and to use the new registers, you get 22-bit
memory addressing like an 11/70. At the time I was there, Able was
supporting RSTS/E and RSX-11M. I don't know what they are doing now.
It is a very clever product. If you are swap bound on an 18-bit CPU, it
can help you a lot. I installed the product at several test sites and
they were all very pleased. However, the product does not give you the
power, separate I/D space or any other attributes of the big 11's, just
the extra memory.
I hope this has helped.
Note, as I said, I no longer have any connection to Able Computer
Technology, Inc.
--
Ted Marshall ...!ucbvax!mtxinu!blia!ted <or> mtxinu!blia!ted@Berkeley.EDU
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