Hi Errol,

 ES>  There was also one which ran at 12mhz,

No there wasn't.

 ES> but I dont think it really got off the ground.

It didn't get past an unreliable prototype (so technically it never
existed).

 ES> (suppliers made some then stopped supporting 64s..). A shame

Wank !

The was never any made.. this was another of John Brown's (JBEE,PARSEC)
projects..  he took money in advance, despite the fact there were no
working units.. and finally after two years the project was dropped.
Some money was refunded, others are still waiting.. the latest "rumour"
is that this zip board was to be replaced with a cartridge speedup
device.. as far as anyone is aware this is more of JB's hot air.

 ES> the time/money/inspiration I'd like to
 ES> try and make one of these but I'm
 ES> not sure on how the fast processor
 ES> interacts with the VIC/SID chips when
 ES> they are still running at 1mhz..

Both the VIC and SID chips are only capable of 1mhz operation.
The turbomaster CPU (4mhz) overcome this limitation in a very crude but
effective way by actually banking the CPU's in and out ! Essentially
the 4mhz CPU was doing all the processing, updating screen ram etc,
then it passed control back to the internal CPU for the the "mundane"
tasks of actually outputting the data (well, thats the way I understand
it to work).

It worked *remarkably* well.

Cheers
Rod
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