Quote:
Originally Posted by ajgriff
One thing worth noting is that Colin's PET is fitted with sixteen TI 4108 dynamic RAM chips (see post #8) whereas the circuit diagram we've been working from has sixteen 4116 chips ie, as in the PET 3032. This is significant because I can't find anywhere currently selling legacy 4108 chips. On the other hand NOS 4116s are still available, possibly because some versions of the Spectrum used them. In fact there's one vendor offering eight 4116s for £10 plus £1.60 p&p. In theory and with changes to jumper settings it would appear that eight 4116s could be used as direct replacements for the sixteen 4108s in Colin's machine.
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If the buffers check out and with Colin's ability to socket multi-pin ICs it's well worth considering these:
https://www.ebay.co.uk/itm/STC-4116-D-memory-ic-ram-QTY-8/393015482007?hash=item5b818c5697:g7kAAOSwMFhfrqUA
The only problem is I can't find a datasheet for these STC chips but the seller seems to have dozens of them so upgrading to 32k could even be an option.
Alan