Problem Info needed on how character text is stored in 3P & 3N DK 2 stack original pcb

[myPinballs]

As titled , need some help on what the character map looks like in the 3P & 3N roms on a dk original 2/4 stack.

I have a board with a very weird and intermittent text issue where half the character set will show 2 characters back in the alphabet,
ie
F shows D
G shows E

but
D shows D
E shows E

Any info on the layout would be handy

 

[jerryspaghetti]

I’m not very clued up on this technical stuff but the link below might help you identify the source of the problem…
https://www.brasington.org/arcade/tech/dk/

One thing I’d add is that I think incorrect + or - 5v causes some sprite issues. Especially intermittent ones.

 

[myPinballs]

Yeah already know about this info but this error I need to go much deeper into the roms

 

[jerryspaghetti]

*moonwalks slowly out of the room….

 

[TheDaddy]

@jerryspaghetti Never Apologise for trying to help someone,

Dave.

 

[jerryspaghetti]

View attachment 36231

@jerryspaghetti Never Apologise for trying to help someone,

Dave.

Was just messing haha

 

[jerryspaghetti]

I would ask why you need to delve that deep and not just burn some new roms?

 

[myPinballs]

I would ask why you need to delve that deep and not just burn some new roms?

I'm talking about the layout of the rom design so i can work out what the likely address issue is here . the roms themselves are fine. Fixed ALOT of these boards but this one is strange so was hoping there was a memory map dump out there that i hadn't seen

Anyway, never mind..

 

[jerryspaghetti]

👍🏻

 

[jbtech]

Hi, if it helps I do know that the characters placed into the background / text layer aren't ascii based.

Characters 0-9 are represented by codes 0 - 9 hex, a space is 10 hex and alpha characters begin with A at 11 hex. (I nicknamed it donscii)
So D and E would be 14 and 15 hex while F and G would be 16 and 17 hex. It does look like bit 1 is being dropped from the character address.

I haven't mapped out the character roms themseves so not sure where the characters begin exactly.
There is a disassembly of the program ROMs here if you haven't already seen that. https://github.com/furrykef/dkdasm

Hope that helps. I have a little RAM test for DK but assume it's not a RAM issue if only text characters are affected.

Regards, John.

 

[Lurch666]

I have used Omnivore before to see how graphics in a rom are stored.
Dunno if it will help in your case but it's worth a try.

 

[jbtech]

Oh, here is 5K



It does start at 00 and each character is 8 bytes so I guess to slip back two letters it could be bit 5 missing from the ROM address...

 

[jbtech]

Oops, bit 4 sorry

 

[myPinballs]

Many thanks for the info everyone. The issue is very intermittent hence wanting to work backwards from the rom images disassembly. Thanks for the info on the tool able to view inside roms graphics etc.

 

[myPinballs]

I think a ram swap at 2P has solved it. On for an hour plus this morning no issues. So bit 1 was likely issue though intermittent shorting low