11/45 hack?

Noel Chiappa jnc at mercury.lcs.mit.edu
Mon Feb 9 06:38:42 CST 2015

    > From: Paul Anderson

    > it's not part of the 128 kw or 256 kb limit of the 45

Err, don't think so - that limit is in the addressing hardware in the CPU
as well as in the UNIBUS.

    > From: Eric Smith

    > The 11/45 (or 11/50, 11/55) Fastbus memory, whether MOS or bipolar, is
    > not directly on either Unibus

Actually, my understanding is that it is on UNIBUS B (or 2), via a second port
to the memory; see this post:


which gave my understanding of how it works. And of course if you connect the
two UNIBI together, it's therefore directly on UNIBUS A (or 1), as well. I.e.
DMA devices can do transfers to/from it.


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