CDC 6600 emulation - was Re: How do they make Verilog code for unknown ICs?

Chuck Guzis cclist at
Tue Jun 21 12:02:31 CDT 2016

On 06/21/2016 09:24 AM, Paul Koning wrote:

> I don't recognize "ILR".  The control for central exchange (XJ
> instruction) is is largely in the ECS coupler partly because some of
> the exchange package state (RAX/FLX/MA) lives there, as does the
> monitor mode flag.  Also partly because XJ and RE/WE are 01 opcodes
> that use the same address calculation.  I think once you get past the
> coupler into ECS itself and the ECS controller, there aren't any
> execution-related bits.  Not unless you count the Flag Register,
> which is a set of mutexes operated on by ECS read/write operations.

ILR = "Interlock Register"

It was mutex setup, but on a per-system, rather than as a global ECS
thing like the flags register--and accessible only to PPs.  Any word in
it could be read by any PP.

Either 64 or 128 bits located on PP channel 15 (octal).  The only
mention that I could find of it in the bitsavers collection was for the
Cyber 74, but it was on lower Cybers as well.

PDF page 48.

I don't know if it was a retrofit for older 6000 systems, but it would
seem to make sense if it was.  It simplified the RCH/DCH PP channel
reservation calls enormously.


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