6502 stack pointer is 8 bits

[BigEd]

Untested - but it seems wrong to me and a simple fix. Unless I missed something.

[hoglet67]

It is actually exposed by the hardware as a 16 bit value:
https://github.com/hoglet67/AtomBusMon/blob/master/src/T6502/T65.vhd#L209
and
https://github.com/hoglet67/AtomBusMon/blob/master/src/AlanD/R65Cx2.vhd#L1522

I'm not sure why in the T65 core S is 16-bits; possibly because the core also claims some degree of 65C816 compatibility.

I stuck with 16 bits so the value displayed to the user is actually the memory address being pointed at.

Dave

[BigEd]

Ah, right, the '816 - support for which in T65 is very slight, AFAICT, but the intention is there.

(In the stardot thread the value displayed is not a normal 6502 stack value, which would always be in page one. That seems odd. Perhaps the T65 masks the high byte when in '02 mode and it is essentially uninitialised.)

[hoglet67]

Ah, in that case this is a bug....
#2

I think the best solution is for the C code to force the upper 8 bits to 0x01, i.e. ignore what the hardware is telling it.

[BigEd]

Sounds like a plan!