PET 6540 ROM operating temperature

drlegendre . drlegendre at
Wed Nov 19 20:02:03 CST 2014

IME, older ROM chips can get +quite+ warm.. but 'painful' is fairly
subjective. I seem to recall ROM chips running hotter than the 6502/6510
CPU in some of my Commodore stuff.

Do you have any way to quantify the temperature? A little HS compound & a
digital cooking thermometer?

On Wed, Nov 19, 2014 at 7:47 PM, Josh Dersch <derschjo at> wrote:

> Hey all --
> A quick one -- what's the normal operating temperature for the old MPS6540
> ROMs used in the original Commodore PETs?  I noticed last night after
> running mine for ~30 minutes that the ROMs were very hot, to the point of
> being painful to touch.
> The machine is running fine as far as I can tell -- though I haven't
> verified the contents of the ROMs, BASIC runs without any apparent issues.
> Voltages are normal (just a shade under 5V).
> I've not experienced ROM chips that run so very hot -- is this normal?
> Thanks,
> Josh

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