Question for support for XTAL based CPU's (6800/6808)

[jessaskey]

Wondering if emulating CPU's such as the 6800 and the 6808 (XTAL version)... might be doable similar to the 6809(XTAL) and 68098E? I saw Dave's post back on Oct 9, 2018 about the E-Mode jumper on the GODIL adapter, but I also saw that the EEPIZZA adapter dropped support for the 6809... was it problematic or just not doable on the EEPIZZA I/O? To support XTAL CPU's then I suppose a clock generator would need to be added onto the adapter PCB?

I know you previously discussed adding 6800 support since it is quite similar to the 6809 and has a decent vhdl core already made. I would be interested in KICAD'ing up an adapter PCB (EEPIZZA).

thank you

[hoglet67]

Wondering if emulating CPU's such as the 6800 and the 6808 (XTAL version)... might be doable similar to the 6809(XTAL) and 68098E?

It would be certainly be possible. At the time I was actively developing this, I didn't have any 6800 based machines, to test on, so that's the main reason there isn't one.

I've since picked up a MEK6800D2:
https://retrocomputingforum.com/t/unusual-6800-microprocessor-trainer/4220

I saw Dave's post back on Oct 9, 2018 about the E-Mode jumper on the GODIL adapter, but I also saw that the EEPIZZA adapter dropped support for the 6809... was it problematic or just not doable on the EEPIZZA I/O? To support XTAL CPU's then I suppose a clock generator would need to be added onto the adapter PCB?

It was problematic to make a common level shifter board that would work with both E and None-E parts, because several pins change direction between the two parts:

It's quite unwieldy to do this with the 74LVC4245 level shifters (it would have added a couple more of these to the board).

This isn't an issue with the FET-based level shifters (like the GODIL uses) as they work in either direction. But they have other issues, hence me preferring the 74LVC4245.

I know you previously discussed adding 6800 support since it is quite similar to the 6809 and has a decent vhdl core already made. I would be interested in KICAD'ing up an adapter PCB (EEPIZZA).

Feel free to have a go - I don't see any insurmountable issues.

Do be aware that the EEPIZZA board is no longer available, so you might want to consider the Cyclone 10 board being used in the newer adapters in #17.

Dave

[jessaskey]

Okay, thanks, let me chew on this and see if I can actually put some time to it. Probably just make a separate adapter for the XTAL vs clocked CPU then really. I specifically have a project that uses the 6808 (XTAL) so that is my primary use case right now. Are the old 6809 adapter schematics available as I should be able to just pin swap those into a new KICAD 6808 adapter (EEPIZZA).

On the topic of the EEPIZZA, completely understood that they are gone but since I have 3 of them and already have your 6809E, Z80 and 6502 adapters built for that (they are great!!!! Super Appreciative!), Im going to stay on that track. If I have to go to the Cyclone 10, I suppose I would just make an adapter that goes from the EEPIZZA connectors to the Cyclone rather than making all new adapters for the Cyclone.

[hoglet67]

Are the old 6809 adapter schematics available as I should be able to just pin swap those into a new KICAD 6808 adapter (EEPIZZA).

The EEPIZZA 6909E Adapter schematics are here:
https://github.com/hoglet67/AtomBusMon/wiki/6809E-CPU-Adapter
https://github.com/hoglet67/AtomBusMon/tree/master/kicad/6809e/v1

For the older GODIL version (6809/6809E), there is no separate adapter, just the GODIL module.
https://www.trenz-electronic.de/trenzdownloads/OHO-Elektronik/TE0261-GODIL/archive/UM_GODIL-v090.pdf

On the topic of the EEPIZZA, completely understood that they are gone but since I have 3 of them and already have your 6809E, Z80 and 6502 adapters built for that (they are great!!!! Super Appreciative!), Im going to stay on that track. If I have to go to the Cyclone 10, I suppose I would just make an adapter that goes from the EEPIZZA connectors to the Cyclone rather than making all new adapters for the Cyclone.

That makes complete sense. I also still have several EEPIZZA boards, which is why I haven't got around to redesigning the adapter boards.

I also find myself used the logic analyzer based decoders for system/software debugging in preference to the ICE:

• 6502 Decoder (does 6502/65C02/65816/6800/SCMP)
• Z80 Decoder (does Z80)
• 6809 Decoder (does 6809/6309)

Using a cheap (£10) FX2 based 16-bit USB Logic Analyzer, these all get you to a instruction trace with full register state.

???? :          : RESET !!      A=?? X=?? Y=?? SP=?? N=? V=? D=? I=1 Z=? C=?
D9CD : A9 40    : LDA #40       A=40 X=?? Y=?? SP=?? N=0 V=? D=? I=1 Z=0 C=?
D9CF : 8D 00 0D : STA 0D00      A=40 X=?? Y=?? SP=?? N=0 V=? D=? I=1 Z=0 C=?
D9D2 : 78       : SEI           A=40 X=?? Y=?? SP=?? N=0 V=? D=? I=1 Z=0 C=?
D9D3 : D8       : CLD           A=40 X=?? Y=?? SP=?? N=0 V=? D=0 I=1 Z=0 C=?
D9D4 : A2 FF    : LDX #FF       A=40 X=FF Y=?? SP=?? N=1 V=? D=0 I=1 Z=0 C=?
D9D6 : 9A       : TXS           A=40 X=FF Y=?? SP=FF N=1 V=? D=0 I=1 Z=0 C=?
D9D7 : AD 4E FE : LDA FE4E      A=80 X=FF Y=?? SP=FF N=1 V=? D=0 I=1 Z=0 C=?
D9DA : 0A       : ASL A         A=00 X=FF Y=?? SP=FF N=0 V=? D=0 I=1 Z=1 C=1
D9DB : 48       : PHA           A=00 X=FF Y=?? SP=FE N=0 V=? D=0 I=1 Z=1 C=1
D9DC : F0 09    : BEQ D9E7      A=00 X=FF Y=?? SP=FE N=0 V=? D=0 I=1 Z=1 C=1
D9E7 : A2 04    : LDX #04       A=00 X=04 Y=?? SP=FE N=0 V=? D=0 I=1 Z=0 C=1
D9E9 : 86 01    : STX 01        A=00 X=04 Y=?? SP=FE N=0 V=? D=0 I=1 Z=0 C=1
D9EB : 85 00    : STA 00        A=00 X=04 Y=?? SP=FE N=0 V=? D=0 I=1 Z=0 C=1
D9ED : A8       : TAY           A=00 X=04 Y=00 SP=FE N=0 V=? D=0 I=1 Z=1 C=1
D9EE : 91 00    : STA (00),Y    A=00 X=04 Y=00 SP=FE N=0 V=? D=0 I=1 Z=1 C=1
D9F0 : C5 01    : CMP 01        A=00 X=04 Y=00 SP=FE N=1 V=? D=0 I=1 Z=0 C=0
D9F2 : F0 09    : BEQ D9FD      A=00 X=04 Y=00 SP=FE N=1 V=? D=0 I=1 Z=0 C=0
D9F4 : C8       : INY           A=00 X=04 Y=01 SP=FE N=0 V=? D=0 I=1 Z=0 C=0
D9F5 : D0 F7    : BNE D9EE      A=00 X=04 Y=01 SP=FE N=0 V=? D=0 I=1 Z=0 C=0