On 07/14/2015 12:55 PM, William Donzelli wrote:
...I/O processors.
I do not think you can claim that the 6600 I/O processors were all
that new. Many (most?) of the 1960s mainframes before the 6600 had
channel controllers.
Perhaps not, but they were unique in their implementation (one "logic
core" multiplexed among 10 memories and register sets) and the
application os same. Prior to about 6000 SCOPE 3.4, most of the OS
logic was present in the PPUs, not the CPU. IIRC, in SCOPE 3.3, the
only CP part of the OS was the storage move program. PPs communicated
among themselves and used numerous "overlays" to accomplish the
supervisory funciton. You could have the CP at a dead stop with the OS
happily ticking along. SCOPE 3.4 moved more of the functionality
I don't think that was ever done with earlier machines.
In contrast, almost none of SCOPE 2 for the 7600 was in the PPs, which
had access only to pre-assigned buffers in CM (or SCM if you will).
7000 SCOPE was implemented using an interesting system of overlapping
field lengths, such that the user program was the innermost.
I've never heard of an operating system, handling all job supervisory
functions and I/O in a S/360 channel.
--Chuck
