Wow, that was a more detailed answer than I was expecting to see. Thank you very much. :)

Now I remember what I'd forgotten: That the 6502 makes relatively extensive use of "dynamic registers," which as you say work just like DRAM: They need to be constantly refreshed. I didn't even think of a ...

Hi everyone, I'm back to trying to figure out the internal structure of the 6502 chip, and I thought I'd ask a question about how data gets to the ALU. Does anyone know if the ALU has input registers or not? When looking at Hanson's block diagram, there are clearly two items labeled "A input ...

How? 74 logic? Programmable logic? Something else?

Mostly 74 logic. I expect to use a ROM microcode, but I'm hoping everything else can be 7400-series chips. Because the intent of this project is really to open up the 6502 as much as possible so that everything is accessible to oscilloscope ...

Thank you, everyone, for your excellent input; I didn't realize that you could do a shift-left by simply adding a number to itself, although of course it seems obvious now that I think about it. :) I was aware of that huge PostScript file containing a schematic of all the FETs in the 6502, but hadn ...

Hi everyone,

I'm just trying to figure out the pinout for the 6502's ALU. I found that picture that everyone uses to reference how the 6502 works inside (http://homepage.mac.com/jorgechamorro/a2things/6502.jpg) but I only see 5 instruction inputs for the ALU: SUMS, ANDS, EORS, ORS, and SRS. It ...