Booting an IBM MP 3000 S/390 System

Eric Smith spacewar at
Thu Aug 6 14:03:37 CDT 2015

On Thu, Aug 6, 2015 at 9:27 AM, Jay Jaeger <cube1 at> wrote:
> The  PDP-10 had a PDP-11 console processor.

The early PDP-10 models used the KA10 and KI10 CPUs, which did not
have any separate processor for console/boot/diagnostics. It was
common, however, to have a PDP-8 based communication subsystem, such
as the 680 or 680I.

The later models, using the KL10 and KS10 main CPUs, had console processors.

The KL10 used a PDP-11/40 console processor, which had special access
to the KL10 diagnostic data paths, and an RH11 Massbus adapter to a
dual-port of one of the RP06 drives. In a DECsystem-10, it also had
DECtape or floppy, and only handled boot, diagnostics, and the console
terminal (usually an LA36 DECwriter). In a DECSYSTEM-20, it had
floppy, and also handled additional terminals and unit-record

KL10-based DECsystem-10 configurations and larger KL10-based
DECsystem20 configurations tended to have additional PDP-11
communication processors; all but the smallest KL10 CPU configurations
could support up to four DTE20 (DEC Ten to Eleven) Unibuses, one of
which was for the PDP-11/40 console processor.

The KS10 used an 8080-based console subsystem for the same purposes.

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