Ideas for a simple, but somewhat extendable computer bus

Noel Chiappa jnc at
Mon Nov 20 19:50:39 CST 2017

    > From: Charles Anthony

    > a hybrid PDP-11 (16 bits) / PDP-15 (18 bits) on a shared bus (UNIBUS?)

That's a UNICHANNEL-15: it allowed devices on the -11 to do DMA directly into
the PDP-15's memory through the MX15-B Memory Multiplexer.

Odd factoid: this UNIBUS could run in 18-bit mode (!!), where the UNIBUS' two
parity lines were recycled into 2 extra data lines. Some DMA interfaces (e.g.
the RK11) could support this; in this particular case, it allowed the PDP-15
to use RK05 drives.


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