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Overclocking the machine

Posted: Fri Apr 12, 2019 8:58 am
by RS232
Just wondering if anyone has looked into overclocking their machine yet?

Re: Overclocking the machine

Posted: Fri Apr 12, 2019 9:24 am
by McKlaud
Yes, it was done in some clones in the past. It is very well described there: http://www.user.dccnet.com/wrigter/inde ... /turbo.htm.

Re: Overclocking the machine

Posted: Fri Apr 12, 2019 11:00 am
by 1024MAK
Andy (a member here) has seriously overclocked a ZX81. However he was using his older ULA replacement module.

With a standard Sinclair ULA, overclocking is difficult as you can’t change the frequency without messing up the screen display.

Mark

Re: Overclocking the machine

Posted: Fri Apr 12, 2019 10:37 pm
by Andy Rea
1024MAK wrote:
Fri Apr 12, 2019 11:00 am
Andy (a member here) has seriously overclocked a ZX81. However he was using his older ULA replacement module.

With a standard Sinclair ULA, overclocking is difficult as you can’t change the frequency without messing up the screen display.

Mark
Slight correction, the older ULA could do 2X speed... my special 1 of a kind zeddy , whilst based on that older ULA its very different and the cpld is on a break out board so that i could use all the IO it goes 20Mhz flat out and runs 3.333Mhz at normal speed ( 20Mhz / 6 ) it also benefits from completely split busses so no resistor isolation bridges are needed.

the Wilf Rigter pages are awesome !

Regards Andy