Without knowing the details, I think I can ask this question: Have you tried reading the suspect ROMs with your programmer and comparing that data to a known good ROM image?

If the read fails, that might indicate a problem with the chip. If the read is successful, but corrupt, you might be able to re-program that chip with a good image. If you chip's capacity is some multiple of the ROM image, just keep concatenating the ROM image on until you have an image the right size for your chip. That way, bank selection won't be an issue.

Originally Posted by grinder2112

I've been trying to simplify the conversation by asking a single, straight-forward question at a time. Your data dumps undoubtedly contain useful information, but its not progressing my understanding. So, let's take this a step at a time.

My current understanding:

1) You have multiple PCBs that you suspect have corrupted ROMs.

2) Those PCBs have their original ROMs, which are using 8KB (64kb) EPROMs.

3) None of the PCBs have been reworked to enable some sort of multi-ROM selection.

Is this correct? If not, concisely give me the correct information.

I think I might have some good advice, but I need to understand your situation first, so I don't end up dispensing *bad* advice.

Answers to questions:
1) Yes, two of them
2) Original ROMS but sockets are 24pin , ROMS are 4kb (32kbits 2532 ROMS)
3) None yet

See my answer at KLOV forum and my pictures of the ROMS. There I also explain what ROMS I do have.
One guy also raised the issue of legitimately of ROMS.

https://forums.arcade-museum.com/thr.../#post-4253449

Quoting myself here from KLOV forum to make this thread more complete due to the legitimately issue which has to be dealt with here at TG.

"Now - I cannot have original labels on the ROMS becuase those were printed 1980s by Bally Midway.
Not manufactured anymore. The pictures below you will see MikesArcade did post labels on it 5E and 5F but not the printed label as from a factory.

My ROM Images: https://drive.google.com/drive/folde...-Y?usp=sharing

Today ROMS are bought from Arcade shops that just uses refurbished 2532 and write the exact same image to that EPROM.

One of my Pacman PCB do have at least two Hitachi ROM (see pictures) written by MikesArcade because there were no other original old ROM to fit but they have used the exact same ROM image on a 2532. I have asked Mark Hoff to get me two MsPacman PCB where I can legitmally play for WR and these are the PCBs I did got (as bought from MikesArcade).

Both of them were 100% working when I got them but I did a terrible mistake......

I did switch my cabinet on see if the PCB's boot.. all goes well...while I was make corrections to the inside of the cabinet
I bore some holes with a drill, I forgot that my cabinet was still running, so I got a surge on the same power line!!!

One PCB gave me strange screen errors (invalid ROm for 6F) and the second one with (speedup 6F) did work 100%.
Did play about 20 killscreens with speedup version 860K to 936K. Wanted to play normal speed and pacman.

So I tried replace the 6F speedup with 6F normal speed from the broken PCB to the working one and somehow I broke off a pin and interfere with the voltage. Now speedup also do not want to boot.

Something did happen now I need to fix it.

On ROM: Taking a old working 2532 and a 2764 written EPROM one and when you do the checksum on the 2764 it is the same."

So my question is: "What does a legitimate setup for WR mspacman means? Given situation I am in?

So to have legitimately setup for WR mspacman means I cannot uses the switch setup using MsPacman Bootleg roms between games but I can use that on my second PCB to practice between the games.

So do you then believe that labelled ROMs are needed ? which are not possible in most cases becuase there are very few real mspacman and pacman roms still running alive.

Most of the ROMS, as in the PCBs I got from a trustworthy guy (MikesArcade), do have two Hitachi 2532 ROMS manually written with the original images."

From the KLOV Forum, about legitimacy of using an EPROM 2764 adaptor in a 2532 ROM socket enable 2764 EPROMs instead of a 24pin EPROM:

Hi Mattosborn



Yes I am a member of TG forum. I am the World Record holder of Ms. Pac-Man (speedup) on MAME platform.



Yes, I know the TG rules are original PCB.


In this case where I do have the original PCB with original chips but I messed up my PCB (one or more defunct). I tried with chips that could replace using non-standard 28pin EPROm instead of 24pin standard EPROM layout with same checksum ROM image. It is on this aspect I was not sure therefore I do ask the question. Here I thought becuase the PCB is original I just fixing the ROMS, it would still be legitimate.



Thanks many for your opinion.



I also did asked David Race, Wr on Pac-man his view, here is his response:

Discussion:

Francoisadt: (abreviated version)

Hi David, Please seemy post at KLOV, I do burn with the exact same encrypted original ROM but on a 2764 instead of a 2532. I do not have access to 2532 nor an EPROm programmer do so.

David:

"If the chip types are the same as the original, then burning original code should be legitimate. If the 2764 is of the same family as 2532, I wouldn't see a problem. It would be akin to using different versions of the Z-80. As long as the chips aren't hacked or use any external hardware in conjunction with the original PCB, I don't see an issue with it."



Francoisadt: No the 2764 is not of the same family, got 28pins and not 24pin. The extra pin 2 (A12) is tied to ground, so usage there, so no extra voltage or interaction, just first higher bank of the 8kbyte EPROM is read as if from a 2532 4kbyte.



David:

"Honestly, I wouldn't attempt an official run unless the locations on the original board use the same family of chips-which would mean the same number of pins. I am not really someone that can decide any way. I would ask whoever is in charge of adjudication on the scoreboard of your choice. They may say it is fine, or they may have concerns. Sorry, this is just me.



Francoisadt: Thanks David your opinion is valuable. This mean my workaround setup will not be ligitamate but I can use it for practice once fixed.



Everyone:

Thanks a lot to everyone that did reply, I learn more on some pin mapping and memory addresses from reading "Pacman Problem child" thread response to "Arcade single ROM" responses. I am no expect in electronics therefore the reason for my questions here. Thanks for all the very good answers.

So to summarize:
If a 28pin EPROm is used instead of 24pin EPROM with same ROM image, 28pin been mapped to the exact same pins.
What is everyone's opinion on this? Legitimate or not?

If anyone every wants to make an adaptor for his 2532 socket (no WR run):
2764
A0-A11 -> 2532: A0-A11
A12 -> GND
Q0-Q8 -> 2532: Q0-Q8
VPP -> VCC
~E (pin 20) -> GND
~P (pin 27) -> VCC
~G (pin 22) -> 2532:~E/P (pin 20)

I can't see how a different EPROM chip could possibly grant you a competitive advantage.

Back to the technical issue however: Have you tried reading your original EPROMs? Are they in fact corrupt? If they are corrupt, have your tried re-writing them with your programmer?

Originally Posted by grinder2112

I can't see how a different EPROM chip could possibly grant you a competitive advantage.

Back to the technical issue however: Have you tried reading your original EPROMs? Are they in fact corrupt? If they are corrupt, have your tried re-writing them with your programmer?

The ROM chip is corrupt the board test show that it is corrupt.

I cannot rewrite those 2532 with my EPROM Programmer becuase it can write out 2764 compatible.

If you can program one of the new EPROMs that will then work in your PCBs with an adapter, you should be able to build an adapter that allows your programmer to write to the original EPROMs. Alternately, you can likely find a cheap programmer off of eBay that would allow you program those original EPROMs directly.

Have you been able to write to one of the new EPROMs with your programmer?

Originally Posted by grinder2112

If you can program one of the new EPROMs that will then work in your PCBs with an adapter, you should be able to build an adapter that allows your programmer to write to the original EPROMs. Alternately, you can likely find a cheap programmer off of eBay that would allow you program those original EPROMs directly.

Have you been able to write to one of the new EPROMs with your programmer?

\
Hi Grinder

Yes I have thought about doing an adaptor for my EPROM programmer that can write a 2764.
The problem is that 2532 EPROMS need a 25V pulse to "write enable" whereas the 2764 only 5V.
So the circuit in the EPROM Programmer only caters for 5V feed.

So the EPROM Programmer chip that drives the volts and feed to a ZIF socket only
feed 5V to VPP/VCC on the EPROM that needs to be written.

The timing of when to start 25V and when not is also software controlled.
I read that a guy did some workaround on a DIY Adriono Mega chip where
he built two feeds: one to run the EPROM Programmer circuit/PCB doing
the work (5V) and another power supply of 25V that feeds the 2532 chip.

In his case, his software was written by himself and not tied to the EPROM
Programmer own internal memory (firmware) checking which chip are loaded into
the ZIF socket before proceed.

So I need a way of changing firmware allowing all chips.

I also need to find a way to build a secondary circuit tied into the existing so that
one can feed a secondary volt feed to "write enable pin" of the "written/to-be-written-to" EPROM.

See below:
https://www.electronicdesign.com/tec...grammer-mark-1

I am not able to view the circuit designs at the bottom of the article, can you? (I got timeout from the webpage)

Another one for background:
https://www.electronicsforu.com/elec...rom-programmer

Another:
http://85.226.187.247/eprom/eprom-01.htm

Another:
http://electronics-diy.com/electroni...tic.php?id=707

I am by no means an expert in electronic circuit design symbols.

So these symbols and flow is still "greek" to me.

Hi Francois,
Your problem might be more difficult than you think. The game might tell you that some ROMs are faulty, but it doesn't mean that they are. You might have a faulty controller chip that accesses these ROMs (hence multiple ROMs reported as faulty). If one of the address bits is stuck, you might be accessing a wrong ROM (wrong CRC then). First thing I would do is to replace ALL these old Midway sockets for your chips (bad connection will report as a bad ROM, for example). You could be spending countless hours trying to modify it and then find out that it still doesn't work. Yes, it's good to learn how the board of a game that you love works, but you need tools to test it properly. Often, if one chip fails, you might have other intermittent problems that will show up when you start playing the game more often. I'm afraid that even when you fix it, the board still will be on it's last leg, unless properly tested and certain chips replaced as a bulletproof measure.

It all depends how deep you want to get into board repairs or if you just do this to get one board working and hoping that you never have to do it again. It takes time to learn all this stuff and a lot of money to get all the testing equipment. It's a waste of money, if you just do this for one or two boards. While you do all of this, you will not be able to go for the high score you want. There is no guarantee that you will get it to work after all the money and time invested. It's a high risk with a questionable chance for a reward (working board). It might be a small problem or you might still be working on it a year later.

Old chip programmers will do 25V old arcade chips. You would need something like EMP-10, EMP-20 or EMP-30, but you need a parallel port to use them. There are EMP-11, EMP-21 and EMP-31 that use USB, but these are hard to find and expensive. Another one (people say it's hit and miss) could be GQ-4X4. As it's a USB, I would recommend using a power supply or at least make you you use USB 3.0 plug (more milliamps supplied than USB 2.0 ... maybe that's why people had problems).

Like I said, you might do all the work, but there is no guarantee that the board will function and will be reliable. You might want to consider just sending the boards to someone who can fix it for you. Not sure, if you can find someone reliable near where you live, so you might have to send it off to Europe or US. I can recommend one guy that I know a little bit (never met him in person) that fixes arcade boards on YouTube. His name is Sean (Arcade Doc) and that's his channel:
https://www.youtube.com/channel/UCqW...yEDVBXg/videos
He recently renamed his channel to Classic Arcade Repair.


He just happened to upload a Ms. PacMan board repair couple of days ago:

There are more videos with him fixing different PacMan/Ms. PacMan boards. You can see what it takes to repair a board and what he can do. Each case is different. He cleans dirty boards, replaces all the crappy sockets with a new dual swipe, replaces caps, fixes the problems, including doing a preventative maintenance on each board (he knows which chips to replace that a prone to fail these days). He also can modify some boards to use a lower voltage RAM, etc. He resolders header connectors or even replaces them for better connection. Basically, any problem he should be able to handle. That's the one guy I would trust to send my boards in. He can make it (including burning ROMs), so you can easily swap it between PacMan and Ms. PacMan. He will make sure you have proper ROMs for your record attempt (important!).
On top of that he can make a video fixing your board, so you will be able to see what trouble you almost got yourself into;).


He posts his email on his YouTube channel. Don't want to post it here, as email spam bots would get it. Contact him, explain what you want to do and see how much it would take to fix it, including shipping. He has all the tools to program your old ROMs. I would recommend just sending ALL the boards in (he might give you a better deal then) or maybe you can give one of the boards as part of the payment? If you have more than one board, I would recommend keeping two, so you can have one as PacMan and the other as Ms. PacMan, so you don't have to swap any chips all the time. Also, if one board still goes bad in the future, you will have a backup. If you go the chip swap route and one board, you might want to try socketing the chips you swap in an additional socket, so legs of your chips do not get worn out/broken from frequent swaps. Invest some money in a proper repair now to save yourself tons of trouble down the line. In the end you will find that it will be cheaper to send the boards in, instead of buying all the tools needed (unless you want to get into the arcade board repair hobby). Well, whatever you decide, good luck:).