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Old 27th Mar 2021, 12:33 am   #264
SiriusHardware
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Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,482
Default Re: I found it! A very sorry looking MK14.

They always run very, very hot, alarmingly so. Whenever I programme a set for anyone I always warn them about that because they could be forgiven for thinking they were faulty otherwise. I worked out once that the PROMS consume 2/5ths of the entire current drawn from +5V by a fully populated MK14. You could always try putting little heatsinks on them I suppose but that would give them a non-original appearance. I quite often see heatsinks added to Sinclair ULAs, another famously hot-headed series of ICs.

Just lately I experimented with pin-compatible PROMS from other manufacturers, first the N82S131 from Philips / Signetics which also runs quite warm, possibly not quite as hot as the Nat Semi devices.

Then more recently I bought a pair of the AMD 27S13As offered here on the forum by kan_turk and although they still warm up they don't seem to run anything like as hot as the Nat Semi devices. Tim has those now, but I don't imagine he will have run them for long enough to notice.
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