Re: Pet 65816 accelerator card: Would this work in an Apple //?

[mdj <mdj.mdj@gmail.com>]

On Friday, 12 October 2012 15:12:34 UTC+10, BLuRry  wrote:
> http://www.6502.org/users/andre/adv65/pet816/index.html
> 
> 
> 
> This is a rather interesting accelerator project that puts a zip-style accelerator in the 6502 socket of a Commodore Pet.  It has the appropriate ram and clock sync that you find in a Zip accelerator.  There is also a fantastic writeup that explains the timing characteristics and phase sync behavior in there.  So... what would prohibit this from working in an Apple ][?  Platform-specific MMU behavior?  Interactions with the card I/O?

You've basically summed it up - you need to implement the slowdown technique for the correct memory ranges, and preferrably add the softswitch controls the Zip has to disable slowdown for specific slots.

The other trick of course is handling the Apple II MMU - firstly the Language card logic needs to be replicated, then handled for the Auxiliary bank if you want IIe/IIc support, and arguably generalised to handle RamWorks memory as well if you want it to be truly useful.

Matt