Comment deleted by abc.

Very cool. Thanks! I am working on modelling a rotating drum sequencer Like those that preceded the IBM 650. This is a great reference.

this is righteous

This is cool ,but why does the program counter count 0 8 1 9 2 A... instead of 0,1,2,3,4...

@Aiex2 it seems like it's simply splitting the ROM into two portions. The top two rows of hex entries are the instructions,
while the bottom two rows are the numbers. This way, it's better organized. It would be pretty hard to wrap your head
around instructions if they were sequential.

How were the C39, C40, C41 and C43 names chosen? What logic is there behind them?

David Stevens
http://joshcorbin.com/sap-1-complete/ This sap circuit was taken from the Logisim implementation of the same.

Comment deleted by herty10.

Maybe @DavidStevens Those are models of stuff and those ones worked.

Hi, I'm also developing a simple computer but I don't understand most of the stuff you put there.

My best guess at the nomenclature for C39-43 has to do with the encoding of instructions each segment performs. To back this statement up some, take a look at CS-SAP. In it, each sub-circuit is used to re-encode the decoded instructions that are fed from the iDecoder (instruction decoder), and the control signals from T-Clock. As to the exact instruction pattern that this nomenclature follows, I haven't the foggiest.