This is as much of a note to myself as anything.
I need to either step through the game in the mame debugger or disassemble it, or something, to try and work out what's going on and more to the point, why...
I had a PCB on the bench earlier this evening, just giving it a final play test (as best you can, a 4 player game with only a single variable resistor wired up!) and I noticed that the score was going up and being displayed in hexadecimal, not decimal. I could not get my head around how the game could otherwise be working perfectly and yet that was happening.
The CPU running the game was in my Fluke so I put a different CPU in that also happened to be a different make and the score went back to normal. It's not my Fluke, I proved that by removing the CPU from the POD and putting it in the board direct.
So I guess the game must be using one or more instructions that do something different on a Rockwell 6502BP to what they do on a Signetics plain 6502 (and also a MOS 6502 is fine as well, tried a couple). Maybe this is well documented and well known?? I dunno, it's not something I've EVER come across before but hey, I've not done much with Warlords before. I think I've just fixed this one board. Twice!
If anyone has any ideas then I'm all ears as I don't know. That said, it's going to be hard for me to prove after tonight as the PCB is leaving tomorrow
I just want to know which 6502 I should put in the Fluke to provide the best compatibility. I'd hate to think that I've potentially got PCBs here that I've not been able to fix and at the end of the day it boils down to the make of the 6502.
That does actually remind me. I've got a Missile Command that I spent nights and night on, and to all intents and purposes it works 100% except there is a colour missing at the bottom of the screen. I highly doubt it would be this but I'm certainly going to double check
I need to either step through the game in the mame debugger or disassemble it, or something, to try and work out what's going on and more to the point, why...
I had a PCB on the bench earlier this evening, just giving it a final play test (as best you can, a 4 player game with only a single variable resistor wired up!) and I noticed that the score was going up and being displayed in hexadecimal, not decimal. I could not get my head around how the game could otherwise be working perfectly and yet that was happening.
The CPU running the game was in my Fluke so I put a different CPU in that also happened to be a different make and the score went back to normal. It's not my Fluke, I proved that by removing the CPU from the POD and putting it in the board direct.
So I guess the game must be using one or more instructions that do something different on a Rockwell 6502BP to what they do on a Signetics plain 6502 (and also a MOS 6502 is fine as well, tried a couple). Maybe this is well documented and well known?? I dunno, it's not something I've EVER come across before but hey, I've not done much with Warlords before. I think I've just fixed this one board. Twice!
If anyone has any ideas then I'm all ears as I don't know. That said, it's going to be hard for me to prove after tonight as the PCB is leaving tomorrow
That does actually remind me. I've got a Missile Command that I spent nights and night on, and to all intents and purposes it works 100% except there is a colour missing at the bottom of the screen. I highly doubt it would be this but I'm certainly going to double check
