Once we copied the 82S100 to our own NMOS version the ultimate programing of the array was done by the insertion of "diffusion slugs" and "pre-ohmic contacts", layers 2 and 5 if I remember correctly. When we made a batch we would sometimes have half of the run held after making just the first three layers, (held at 1-2-3) which set the number of OR terms if I remember, however we could make some emergency changes just by changing the mask for layer 5 . Layer 7 was the passivation which we sucked at for quite a while. I remember I had a couple of extra OR rows inserted that were kind of meaningless but available for emergency changes. The worksheet we used originally was straight out of the signetics datebook. For the 128 we outgrew the worksheet and made a text file, which was hand administered. We then gave it to the chip layout group (usually called Calma after their CAD system) and they hand entered it. -----Original Message----- From: firstname.lastname@example.org [mailto:email@example.com] On Behalf Of Thomas Giesel Sent: Tuesday, June 05, 2012 3:20 PM To: firstname.lastname@example.org Subject: Re: Commodore PLA equations (complete) > btw, at the end, isnt it all NANDs ? or NORs ? How exactly it's done in the 82S100 is written in its datasheet: It has (up to) 48 product terms which are AND combinations of any of the inputs and inverted inputs. Any of these 48 product terms can be combined to 8 sums, which are OR combinations of the product terms. The final result can be inverted (which is done with the CASRAM output obviously, which re-uses most of the terms of the other outputs). For my PLA clone (which should arrive in the next few days from Donald...) I wrote the terms in exactly this form. Which makes no difference as the CPLD synthesizer/fitter optimizes it anyway, even if it is written in other forms - but it feels more original ;) Skoe Message was sent through the cbm-hackers mailing list Message was sent through the cbm-hackers mailing listReceived on 2012-06-06 05:00:04
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