Re: 65802 vs. 65C02?

[mjmahon@aol.com (Michael J. Mahon)]

In article <9307085f.0303200613.25d333c8@posting.google.com>,
steve@dosius.zzn.com (Dosius) writes:

>jon@i-manila.com (Jon Co) wrote in message
>news:<a2c2f792.0303192201.3d64a452@posting.google.com>...
>> I read somewhere that the //c+ came with some sort of built in
>> accelerator.  could be causing your timing to be somewhat off ?  I
>> never had a //c+ so I couldnt really verify this for sure.  I do have
>> a //c+ keyboard which I plan to transplant into my //c one of these
>> days.
>
>I read that too, a clone of the Zip Chip.  Puts it up to what some
>sources say is 4 MHz and others claim is 8.  Not sure which is
>reliable :\

4MHz is accurate--I've never seen a claim of 8MHz for the //c+,
although there were 8MHz Zip Chips.  You can always verify
these things for accuracy by checking Apple specifications.

>But would that cause a chain of monitor crashes?...

The timing is not the issue--but the monitor code that initializes
the Zip Chip hardware may depend on some extra hardware that
the Zip Chip provides--like a millisecond timer built into the chip
logic, and therefore replicated in an ASIC in the //c+.

You may need to find out more about this logic, to emulate it,
or, more likely, just how to "fake" it so that the monitor initialization
code gets past it.  You may still have issues with any utility that
tries to set the speed or "slot" options of the accelerator hardware.

-michael

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