Re: General 6809 card for 6502 machines

Hi Ruud :)

it's what I want to check in the schematics... to see if phi0 from the 
board can be ignored...

I'll also check the 8032 schematics...


on an apple II (for example) if we were using a different clock for phi2 
it would probably fail

several clock are produced and synchronized  (video / phi0 /  ras / cas 
signals...)


yes a 6502 works at 1 Mhz  with a clock at 1 Mhz

a 6809 works at 1 Mhz but with a clock at 4 Mhz

so except if I missed something in my quick look to  the super pet 
schematics phi0 is feeded in E



Le 18/10/2017 à 11:48, Baltissen, GJPAA (Ruud) a écrit :
> Hallo Didier,
>
>
>> it seems that the super pet 6809 is running with 1 Mhz clock instead of 4
> Never noticed that, bit of a bummer.
>
>
>> mod69 for the sym1 include a quartz... I'll check the SYM1 schematics
>>
>> I guess they have found a way to synchronize  the clocks...
> No, why should the clocks be synchronized? If the SYM1 is as simple as the KIM-1 IIRC then there is nothing dependent of the original clock. If there is a device using a clock, it is PHI2. And you can consider PHI2 as the 6809's E.
> If there was something like the VIC-II of the C64 involved, that would be a complete different story. In the C128 is was solved by running the Z80 at just 2 MHz. And most probably that is the reason why 6809 runs at 1 MHz in a SuperPET.
>
>
> Met vriendelijke groet / With kind regards, Ruud Baltissen
>
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