--- Richard Erlacher <edick_at_idcomm.com> wrote:
> It would have been difficult for them to do, since the CPU didn't have that
> capability. The Z80 had a hardware refresh cycle built into its operating
> circuitry. It had a refresh counter (though only 7 bits) which was placed on
> the address bus while the CPU decoded an opcode.
I realize that. I think what I was being told about was a refresh system
that depended on some line out of the CPU to tell when it was safe to do
a refresh cycle. The CPU locks up temporarily and blocks the refresh
accidentally until it recovers.
> >
> > The microcode faults I was told about for the XC68000 (not MC68000) would
> >
> The XC68000 was the designator for the earliest units, primarily engineering
> samples of the various masks...
Yes. My boss still has ours. It has a serial number (#424) engraved on
the lid. We were told that the first 400 were for internal Motorola use.
-ethan
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Received on Sat Jul 07 2001 - 08:34:33 BST