Re: about accelerator chips/cards

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

damage_x@hotmail.com wrote:

>I have found some general info about accelerators and I think it would
>be cool to have one for my IIGS. But, what I'm really curious about is
>the practicality of using these products to accelerate other 65xx-based
>systems. Would a Rocket Chip drop right in an Atari 800 for instance?
>Can anyone who's familiar with these things comment?

An accelerator using the same principles could be used for almost
any machine, but the ones designed for Apple II's are specialized
in the way that they are controlled.

The modes and registers in the Rocket Chip (and the Zip Chip, of
which it is a clone) are accessed by multiple references to certain
addresses which are mapped to I/O space in the Apple II.  And the
chip monitors certain I/O addresses to slow down for sequences of
instructions which are timing-critical (such as 5.25" disk access in
the Apple II).  These features are specialized to the Apple II architecture.

Under the right conditions, one of these chips might work in another
1MHz 65C02 machine, depending on whether speed-critical routines
were involved and how the address space was allocated.

-michael

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