Hello.

I can answer both of your questions posted above.

For the first question, SB and IDB (DB) are 04 due to the ALU output layer being connected to SB by dpc19_ADDSB7 and dpc20_ADDSB06. IDB is 04 also because dpc25_SBDB is connecting SB and IDB to each other. The ALU output is 04 due to the ...

An afterthought: the mention of TZPRE in Dr. Hanson's diagram really needs a horizontal negation bar over it to indicate active low.

My thanks too, for determining TZPRE. I was also wondering what it mapped to in visual6502.

I have an additional 2 cents about its naming. In visual6502, node 792 has a name of ~TWOCYCLE.phi1 in the nodenames section. This also supports the conclusion of it being the TZPRE signal, as it has its ...