Is The M9312 Boot Module Essential?

Fritz Mueller fritzm at fritzm.org
Sat Feb 26 12:49:01 CST 2022


> On Feb 26, 2022, at 2:19 AM, Noel Chiappa via cctalk <cctalk at classiccmp.org> wrote:
> So, either (console halt, or a HALT instruction) will cause the identical
> response in the processor; see Section 4.10.3 "Halt Grant Requests": the CPU
> sends HLT GRANT to the console, which returns SACK. As long as SACK is
> asserted, the processor waits with its clock inhibited:

Ah, interesting!  I had no idea the console(s) used SACK to interact with the CPU in this way.  That’s a useful tidbit to tuck away for future reference.

> If there's a broken grant chain, then as you originally pointed out, the M9302
> will jam SACK on. The M8264 could not even be there, and nothing would be any
> different. Same thing if the CPU asserts a grant in response to a now-removed
> interrupt request: the M9302 will jam SACK on, etc, etc.

Perhaps the intent was to always use a non-turnaround far side terminator in configurations with an M8264?

	cheers,
	   —FritzM.




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