Re: 8032's 64KB memory expansion

From: Marko Mäkelä (
Date: 2001-05-08 09:22:34

On Tue, 8 May 2001, Marko Mäkelä wrote:

> The "some extras" must involve hardware
Sorry, I meant "cooperation of hardware and firmware", something what a
freezer cartridge such as the Action Replay does.  The "suspend" mode
would trigger an NMI and force a ROM bank switch, and the NMI handler
would save the state of all chips and registers into normally inaccessible
(battery-backupped) RAM.  The reset routine would check from this special
RAM if the computer was suspended.  If it was, it would restore the state
of all I/O chips.  Of course this doesn't work for all chips or for all
registers.  You can't read the SID chip registers.  Some VIC-IIe and CIA
registers can only be read indirectly (by using delay loops).

Does anyone know how well the Action Replay and other freezer cartridges
capture the state of the I/O chips?


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