Re: 68060

From: Michael Grove <>
Date: Thu, 04 Mar 1999 11:28:54 -0800

Petr Stehlik wrote:
> > When TOS boots, in the first few instructions, it has to
> > setup vector tables. It looks like this is not occurring. If
> > it cannot do this, a double bus error occurs. I don't see
> > this monitoring the bus with a volt meter, but I am not
> > ruling it out.
> > Steve also said there is an illegal instruction for the
> > 040/060 around the sixth or seventh instruction at startup
> > that the AB must be taking care of somehow.
> That's what I was always telling you.

:). I am hard headed.
> > Because there is no screen display, ram is not getting
> > initialized, but that sounds right because it looks as
> > though the vectors are not initialized.
> >
> > I don't know much about this. I think my hardware setup is
> > correct and there is a software problem. I wouldn't have any
> > idea how to correct this other than someone correcting it
> > and putting it into an eprom to try. The cartridge doesn't
> > have enough memory to insert a pair of 512K EPROM's, so it
> > would have to fit in the TOS ROM socket on a 1 meg eprom.
> This is exactly what I want to do - create a 040/060 friendly TOS ROM...
> Wait a few days, I should get the ROM burner really soon.

There is a different meaning of the IPL# during reset
between the 040 and 060. On the 040, during reset, the
IPL#'s defines the cache size. On the 060 there is only one
cache size and the IPL#'s state means something different.
For the 060, there are "040" compatible modes that can (and
should) be enabled for the 060 to work on a "040" system.
IPL2 should be asserted (low) to enable extra data write
hold mode, IPL1 should be negated (high) to enable MC 68040
acknowledge termination protocol, and IPL0 should be be
negated (high) to disable acknowledge termination ignore
state capability mode. You would have to look at the 060
users manual at the reset timing to figure how long to hold
the IPL's. I have tried to do this manually, but it would be
much easier if you could implement this into your modified

I can have someone burn eproms at work no problem. I can get
the eproms delivered in two days. If you have to wait very
long, I could have the eproms burned here and send one to


> Petr
Received on to. mars 04 1999 - 22:29:10 CET

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