Erased Maskroms Irem M92?

[Mrhide]

I have a really clean Irem Skins Games (us set 2) that is ...not booting. aka the black screen

Power is good, cab is good with other boards, etc. I was about to start probing but thought, we not check the roms?

Almost all of them are good, except mt20-ho-a and the maskroms @ c0,c1,c2,c4 (sharp LH532 which thanks to https://snescentral.com/chips.php?chiptype=MASKROM and TwistedSymphony's EPRom cross reference, tells me they are 27c2001) and "da" ( ic8 ) (which is a sharp LH534 aka 27c4001) which are all reading as what I believe is EMPTY? (FF FF FF FF FF FF FF FF FF FF FF...).

I burned the 4x 27c2001 and the 1x 27c4001, expecting a miracle when I boot the board and ... nada. Same nothingness.

So my question is this: What could have wipe these masksroms?! and what else could it have taken out? (like a PAL?)

...which I guess would not help since mame is saying :
skingame2 : mt2eep (2048 bytes) - NEEDS REDUMP
skingame2 : pal16l8-m92-a-3m.ic11 (260 bytes) - NOT FOUND - NO GOOD DUMP KNOWN
skingame2 : pal16l8-m92-a-7j.ic41 (260 bytes) - NOT FOUND - NO GOOD DUMP KNOWN
skingame2 : pal16l8-m92-a-9j.ic51 (260 bytes) - NOT FOUND - NO GOOD DUMP KNOWN
skingame2 : pal16l8-m92-b-2l.ic7 (260 bytes) - NOT FOUND - NO GOOD DUMP KNOWN
skingame2 : pal16l8-m92-b-7h.ic47 (260 bytes) - NOT FOUND - NO GOOD DUMP KNOWN

thanks

 

[stj]

roms of most types are a matrix of capacitors holding a charge.
eventually the electrons escape to the point of a flip from a 0 to a 1.
but if your seeing *all* FF then it's probably just faulty.

slightly related, i'v wondered a few times how easy it would be to liberate those electrons without a UV light.
either by extended durations of heat or by some wavelength of ionising radiation.

that way i could blank and then re-program mask parts

 

[ic3b4ll]

roms of most types are a matrix of capacitors holding a charge.
eventually the electrons escape to the point of a flip from a 0 to a 1.
but if your seeing *all* FF then it's probably just faulty.

slightly related, i'v wondered a few times how easy it would be to liberate those electrons without a UV light.
either by extended durations of heat or by some wavelength of ionising radiation.

that way i could blank and then re-program mask parts

Can't. Mask ROMs are not OTP EPROMs. The fabrication process is very different. A good analogy would be the difference between a CD and a CD-R.
I believe X-rays can erase EPROMs so assuming they penetrate the (plastic) package and there's no shielding, you could probably erase OTP EPROMs. I mean... They just don't have the quartz window for erasing their contents...

 

[ic3b4ll]

I have a really clean Irem Skins Games (us set 2) that is ...not booting. aka the black screen

Power is good, cab is good with other boards, etc. I was about to start probing but thought, we not check the roms?

Almost all of them are good, except mt20-ho-a and the maskroms @ c0,c1,c2,c4 (sharp LH532 which thanks to https://snescentral.com/chips.php?chiptype=MASKROM and TwistedSymphony's EPRom cross reference, tells me they are 27c2001) and "da" ( ic8 ) (which is a sharp LH534 aka 27c4001) which are all reading as what I believe is EMPTY? (FF FF FF FF FF FF FF FF FF FF FF...).

I burned the 4x 27c2001 and the 1x 27c4001, expecting a miracle when I boot the board and ... nada. Same nothingness.

So my question is this: What could have wipe these masksroms?! and what else could it have taken out? (like a PAL?)

...which I guess would not help since mame is saying :
skingame2 : mt2eep (2048 bytes) - NEEDS REDUMP
skingame2 : pal16l8-m92-a-3m.ic11 (260 bytes) - NOT FOUND - NO GOOD DUMP KNOWN
skingame2 : pal16l8-m92-a-7j.ic41 (260 bytes) - NOT FOUND - NO GOOD DUMP KNOWN
skingame2 : pal16l8-m92-a-9j.ic51 (260 bytes) - NOT FOUND - NO GOOD DUMP KNOWN
skingame2 : pal16l8-m92-b-2l.ic7 (260 bytes) - NOT FOUND - NO GOOD DUMP KNOWN
skingame2 : pal16l8-m92-b-7h.ic47 (260 bytes) - NOT FOUND - NO GOOD DUMP KNOWN

thanks

Mask ROMs die. Period. They're not magical. Given they are all bad, I'd say something that they all share (address bus, control pins, ...) died. Maybe one popped and killed the others. Maybe a buffer shorted and took them out.
'Very clean' is really not an indicator of working/not working, I'm afraid.

 

[stj]

i doubt anybody has made mask roms for many decades.
who is gonna generate a mask for a wafer line when they can just factory program an eprom in a cheaper package.
the newer ones may even be custom marked flash chips - that would explain the shit lifespan.

 

[ic3b4ll]

They are still being made. Game Boy Advance games used them and that wasn't that long ago.
But yes, nowadays you'd probably use a flash chip written at the factory with your data
Some late 90s early 00s games used flash. Namco System 11 and Naomi cartridges used them I think.
Packaging is cheap. It's the die inside that's expensive. There's many games that have Mask ROMs in SMD packages. Sharp used to make them, you can even find data sheets for them.

 

[jassin000]

who is gonna generate a mask for a wafer line when they can just factory program an eprom

Really depends on the size of the run... For smaller orders absolutely factory programmed.
For a really large run, like the world wide release of an arcade game, it would be worth the time/money to have a litho mask created.
Its basically the same time to build, only you could side step programming and QC around that action...
Final-FV test before module would always exist in both cases and this would also be the QC for the mask (so again less steps to release once you reach full production).