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?
Marko
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