Reproducing old machines with newer technology

Chuck Guzis cclist at
Tue Jul 14 15:37:16 CDT 2015

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.


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