On Thu, Jul 27, 2017 at 6:33 AM, Noel Chiappa via cctalk < cctalk@classiccmp.org> wrote:
> > > I wish I knew why there were two different kinds of IOM panel, but I'd > only be guessing - I haven't seen anything in the manuals so far. > > I know that the IOMs evolved; starting with the GE era GIOC (Generalized I/O Controller), IOM, IMU (Information Multiplexor Unit), and the NSA (New System Architecture). I have seen references to IOM 6000 and IOM 6000A model numbers. The NSA units duplicated the page table lookup hardware, allow process generated channel programs to do I/O in the process memory space. If one of the IOM panels has any reference to paging, then it would be from the NSA series. The SCU memory size configuration switches would also be a clue. I believe that the early SCUs had a 256K word maximum configuration, the later 4MW SCU a 4MW maximum; the settings on the configuration switches should correspond to earlier or later models, but I don't have any correlation between model names/numbers and capacity. -- Charles
