68020 uP at slower speed than rated

[wn1fju]

I think the Motorola MC68020RP16E microprocessor in my Tek TDS520 scope is hosed.  This is a 16 MHz part.  Can I use a MC68020RP20E part that
is rated for 20 MHz without any problems? 

[Fraser]

Yes.

Microprocessors of this era and architecture were identical dies and were speed selected at time of manufacture. Even the 16MHz unit’s might run at 20MHz but were not guaranteed to do so reliably. A 20MHz MC68K series processor is just one that has passed the higher speed tests and is theoretically a better ‘quality’ than the 16MHz version. In this case, a faster rated microprocessor may be run at a lower clock frequency without issue. Do not be tempted to change the microprocessor clock to 20 MHz though, that can cause complications in the rest of the system.

Fraser

[wn1fju]

Thanks for the info.