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Old 25th Oct 2018, 11:21 pm   #105
SiriusHardware
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Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,484
Default Re: MK14 schematic revisions

Best of luck finding the 8154 RAM/IO (maybe you already have one)- it definitely makes a big difference to the 'play value' of the MK14. I think Forum member GrahamN (who has one of the JM replicas) managed to find some somewhere, though at a price.

One of the things which always gets me about the SC/MP is ... no SUB (subtract) instruction, or at least not one which is immediately recognisable as such. ("CAD", Complement and Add, is the equivalent). Also, no conventional CALL / RETURN instructions and no dedicated Stack Pointer of the type found on virtually all other microprocessors from that time - you can call subroutines, but it involves swapping the contents of one of the pointers with the PC - a bit messy.
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