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

[Phipli]

It is a 256k module …
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Each chip is 4Mbit, so it has an available size of 4MByte (eight chips)? Why do you say 256k?

 

[slomacuser]

Each chip is 4Mbit, so it has an available size of 4MByte (eight chips)? Why do you say 256k?

I was googling for this 341-0741 and found a 256k cache …

 

[Phipli]

I was googling for this 341-0741 and found a 256k cache …

It isn't the same thing. 341-0741 is usually the board for a Nubus mac ROM, but the form factor stayed the same through the beige era. As it has 4MB, it isn't necessarily a Nubus PPC era ROM but might be, and it absolutely isn't a cache because it has ROM chips.

 

[jajan547]

It isn't the same thing. 341-0741 is usually the board for a Nubus mac ROM, but the form factor stayed the same through the beige era. As it has 4MB, it isn't necessarily a Nubus PPC era ROM but might be, and it absolutely isn't a cache because it has ROM chips.

I have a 6150/66 I could try it in and see what it does.

 

[Phipli]

I have a 6150/66 I could try it in and see what it does.

I suspect it is from a 6100 or similar and would boot it. You are really looking for a custom written ROM because 7500s just came with soldered ROMs. Ones people have in drawers are just goung to be almost all Nubus or G3 ROMs.

 

[jajan547]

I suspect it is from a 6100 or similar and would boot it. You are really looking for a custom written ROM because 7500s just came with soldered ROMs. Ones people have in drawers are just goung to be almost all Nubus or G3 ROMs.

Yeah I’m beginning to think it’s impossible but I’d hate to solder to a prototype board.

 

[domii]

My Powercenter Pro mac clone has a apple branded rom socketed dimm. I also have a Power Computing Powerwave motherboard (just the board, missing the combo riser that had nubus and pci slots) and it has a rom dimm also.

The Powercenter is catalyst based and the other tsunami, which I believe is like the 8500. I can take a picture of the rom dimm from that to compare.

​

 

[Phipli]

Just realised this one is a ROM not cache. I got carried away.

 

[Phipli]

Yeah I’m beginning to think it’s impossible but I’d hate to solder to a prototype board.

I'm not sure, but it might be possible to solder the four chips from another 7500 onto a 6100 ROM SIMM? You'd have to get the order right.

 

[jajan547]

My Powercenter Pro mac clone has a apple branded rom socketed dimm. I also have a Power Computing Powerwave motherboard (just the board, missing the combo riser that had nubus and pci slots) and it has a rom dimm also.

The Powercenter is catalyst based and the other tsunami, which I believe is like the 8500. I can take a picture of the rom dimm from that to compare.

​

Do you have photos?

 

[jajan547]

I'm not sure, but it might be possible to solder the four chips from another 7500 onto a 6100 ROM SIMM? You'd have to get the order right.

I absolutely agree and wouldn’t mind that but I don’t want to destroy something like this in the process I want to be sure.

 

[domii]

They are Power computing branded so I don't know.
Also I did swap the rom's around once and they both worked, although one has a newer date to it, so I'll have to boot into open firmware at some point and see what the difference is.

First one is Powerwave PCI/Nubus Mac clone & rom dimm, second is the Powercenter Pro

 

[jajan547]

They are Power computing branded so I don't know.
Also I did swap the rom's around once and they both worked, although one has a newer date to it, so I'll have to boot into open firmware at some point and see what the difference is.

First one is Powerwave PCI/Nubus Mac clone & rom dimm, second is the Powercenter Pro

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Those will absolutely work on a 7500 the bottom especially. Would you see if it boots up an 8500 or something similar. I’d be willing to buy one from you.

 

[slomacuser]

It isn't the same thing. 341-0741 is usually the board for a Nubus mac ROM, but the form factor stayed the same through the beige era. As it has 4MB, it isn't necessarily a Nubus PPC era ROM but might be, and it absolutely isn't a cache because it has ROM chips.

you were right it is not a cache… tested in a 7100

 

[jajan547]

you were right it is not a cache… tested in a 7100

Can you try it in a 7300 7500 8500?

 

[domii]

Those will absolutely work on a 7500 the bottom especially. Would you see if it boots up an 8500 or something similar. I’d be willing to buy one from you.

I don't have any other macs with a rom slot to try them in, but those mac clones where based right of the reference deisngs of that vintage.
Am supprised there is nothing on ebay at the moment. Uh - I don't want to part with mine, but they are a good frame of reference.

I had one guy bookmarked for some parts, he may have some for sale as.

https://www.retrotechnology.com/herbs_stuff/m_power.html#powercomp

 

[slomacuser]

Can you try it in a 7300 7500 8500?

I do not have of these… I will ship you the chips anyway

 

[jajan547]

I do not have of these… I will ship you the chips anyway

That’s awesome!

 

[mgmac]

hi,
are you really sure that 820-0719-B is not correct for this PMac 7500 ?

 

[jajan547]

hi,
are you really sure that 820-0719-B is not correct for this PMac 7500 ?

Isn’t that just a cache?