Q:040/060 MMU and Snooping

From: Michael Grove <mgrove_at_iwvisp.com>
Date: Tue, 09 Mar 1999 11:12:59 -0800

I took a few days break from thinking much about the 060 on
the Afterburner.
Now, after looking through the user manuals I have a couple
of questions.

If the Afterburner Tool Kit that Doug assembled (and the
apps that Overscan provided with the A/B) enable the MMU
'after' the machine has booted, does this mean the MMU is
disabled (MDIS LOW) by the Afterburner during reset and
system initialization, then initializes it by software
during the boot sequence (ala the autofolder)?

According to the users manual;
"MMU Disable disables the translation mechanism of the

If the MMU is disabled during initialization, does this mean
that if TOS sends 030 MMU instructions to the 040/060, that
they will be ignored and no error will occur?

I also am not clear on the snooping aspects of the CPU's and
the A/B. I remember Doug saying the A/B doesn't implement
Snooping, and the option he included in V4.X of the TK kits
is one of his own routines (which I think he recommends in
V5 not to use).

The 060 does not utilize the MI pin of the 040. According to
the 060 docs, this pin must be tied high if it is utilized
on the (040) system the 060 is fitted to. I monitored this
pin with the 040 installed, and there is activity while the
machine is booting, and during execution of applications. It
is pulled low during reset. Could this pin being tied high
continually cause problems with the Afterburner operation
with regards to snooping?

Because the A/B is able to initialize the 040, I still find
it odd that the 060 is not able to properly initialize and
really wonder if it is TOS that is causing the problem here.

Received on fr. mars 12 1999 - 17:12:02 CET

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