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Does anyone have a 7500 ROM SIMM and if not are there modern day programable ones?

Phipli

Well-known member
Just to wrap up... the only ROM I haven't crossed off is ©1993... so is too old for the 7500.

Sorry but none of these ROMs will boot a 7500, and some could possibly do harm (the G3 ones).
 

slomacuser

Well-known member
You have too many parts, it makes me sad because each part represents a dead machine.
Yes I do and I want to get rid off ... so if you find anything interesting let me know :) and I am not a scrapper or recycler ... all this parts were given to me and yes some machines have died
 

Phipli

Well-known member
Yes I do and I want to get rid off ... so if you find anything interesting let me know :) and I am not a scrapper or recycler ... all this parts were given to me and yes some machines have died
It would be great to make a ROM reader so it was possible to read them without putting them in a computer and know exactly what they are. All the 6100 ones will work in any 6100/7100/8100 so they're easy.

The odd one is the one I singled out, it almost looks aftermarket. I hoped it was rewritable but I don't think it is.
 

jajan547

Well-known member
I would suggest asking for one and replacing the chips with ones from a donor board. So you would want one that is wired right and has the right footprint for apple stock 7500 ROMs.
I wish I can make a new one with programmable simms but it’s so strange because there’s no telling what is and isn’t wired right
 

Phipli

Well-known member
I wish I can make a new one with programmable simms but it’s so strange because there’s no telling what is and isn’t wired right
This one really intrigues me.

IMG_20220920_122653.jpg
@slomacuser can you photograph the other side?

The issue is we don't know what it is programmed with, but it is similar to a weird ROM I had in an 8600 (which doesn't need a ROM SIMM).
This is mine :
IMG_20220920_125331_edit_306597569318840.jpg
IMG_20220920_125341_edit_306615719189670.jpg
 

Phipli

Well-known member
its similar but you can tell it’s different by the chip orientation
Chips are oriented the same way. They're not the same PCB layout though, but same chips and almost identical. You need to be comparing my second photo with slomacuser's.
 

jajan547

Well-known member
Chips are oriented the same way. They're not the same PCB layout though, but same chips and almost identical. You need to be comparing my second photo with slomacuser's.
I see what you mean now very bizarre what did yours do?
 

Phipli

Well-known member
I see what you mean now very bizarre what did yours do?
It was in a weird machine that my dad was possibly conned with. It was an 8600/250 "mach5" logic board that someone had fitted to a 200MHz processor to. The 200MHz processor is electrically incompatible with the logic board. I suspect that Apple made the computer fail to boot with the wrong processor, but someone cloned an 8600/200 ROM and fitted it so the computer thought it was the older type 8600.

The powersupply failed after a couple of months, likely due to the wrong processor being fitted. My dad ended up getting another 8600/250, this time fully as it should be. The weird dead machine sat on the side for decades until he sent the logic board to me for something and I was confused why it had a mach5 board, non-mach5 processor and a ROM in the slot and on the board.

Thankfully the board still works.
 

jajan547

Well-known member
It was in a weird machine that my dad was possibly conned with. It was an 8600/250 "mach5" logic board that someone had fitted to a 200MHz processor to. The 200MHz processor is electrically incompatible with the logic board. I suspect that Apple made the computer fail to boot with the wrong processor, but someone cloned an 8600/200 ROM and fitted it so the computer thought it was the older type 8600.

The powersupply failed after a couple of months, likely due to the wrong processor being fitted. My dad ended up getting another 8600/250, this time fully as it should be. The weird dead machine sat on the side for decades until he sent the logic board to me for something and I was confused why it had a mach5 board, non-mach5 processor and a ROM in the slot and on the board.

Thankfully the board still works.
I find that interesting because as I continue to look for my ROM I’ve found that another user one with a 9500 and actually compatible rom (same checksum) said their 9500 had on board ROMs but also needed a simm with ROMs to start up. Link
 

al kossow

Member
@slomacuser are there chips on the other side of this one?
View attachment 46663
If there are it might be what is needed, although may need reprogramming.

Edit : no, sadly it is single write ROMs. It isn't reprogrammable.
Development flash roms existed. You needed a "Flash Gordon" Quadra PDS card to program them. I have a box with dozens of them I'd take an offer for in a private message. It's what we used for ROM development in all the first generation PCI machines
 

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jajan547

Well-known member
Development flash roms existed. You needed a "Flash Gordon" Quadra PDS card to program them. I have a box with dozens of them I'd take an offer for in a private message. It's what we used for ROM development in all the first generation PCI machines
PM coming
 

Phipli

Well-known member
I know the ROMs are online suppose I could flash to a 32 pin plcc?
You'd need to flash it to the 8 chips by desoldering them or making some kind of clip, and you'd need to prep the files to flash by aranging them to match how the simm is wired, which would need to be worked out. Sadly it doesn't look like there is enough room to get a socket over top.

Working out how the data in the chips is organised would be best done by reading the whole ROM simm, then labelling each chip very carefully and reading them individually and seeing how the data is organised.
 

jajan547

Well-known member
You'd need to flash it to the 8 chips by desoldering them or making some kind of clip, and you'd need to prep the files to flash by aranging them to match how the simm is wired, which would need to be worked out. Sadly it doesn't look like there is enough room to get a socket over top.

Working out how the data in the chips is organised would be best done by reading the whole ROM simm, then labelling each chip very carefully and reading them individually and seeing how the data is organised.
I don’t know if I have the smarts for all of that sadly
 
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