20 Nov
2017
20 Nov
'17
5:50 p.m.
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.
Noel