> 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