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Mac LC prototype ROM

kupouzar

Member
In summer, I made a post about my Macintosh LC prototype. The original post is probably lost now.
Anyway, I've managed to replace the damaged logic board with a new one and I fixed a leg on the ROM chip and now it's working! So my question is… Is this an ordinary ROM or is it somehow interesting? Also note that TattleTech says Mac LC (19g). In case anyone is interested, I can also post a ROM dump.
 

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MacKilRoy

Well-known member
The Elsie ROMs are dated June 1990. The LC final candidate ROMs are dated 9/30/90. So these ROMs being just before final candidate makes them quite interesting.
 

joshc

Well-known member
I think early production LCs used these ROMs, I don't think you've got a prototype unless the case of your LC is vastly different to the production one.

Here's an LC logicboard service part with the exact same ROMs on the board: https://www.ebay.com/itm/353948641431
 

MacKilRoy

Well-known member
I think early production LCs used these ROMs, I don't think you've got a prototype unless the case of your LC is vastly different to the production one.

Here's an LC logicboard service part with the exact same ROMs on the board: https://www.ebay.com/itm/353948641431
It is my understanding that some PVT prototypes were shipped to Apple training centers for technicians and phone support staff to learn the ins and outs of the new machine.

After they no longer needed the PVT machines, they were likely taken home by fortunate employees.

It would be interesting whether the logic board itself has a serial number, what that is, and how the case looks. Whether it has a serial number or not as well.
 

kupouzar

Member
It is my understanding that some PVT prototypes were shipped to Apple training centers for technicians and phone support staff to learn the ins and outs of the new machine.

After they no longer needed the PVT machines, they were likely taken home by fortunate employees.

It would be interesting whether the logic board itself has a serial number, what that is, and how the case looks. Whether it has a serial number or not as well.
The s/n on the logic board is unfortunately a bit washed out. No s/n, model name or any other info on the case.
 

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MacKilRoy

Well-known member
The s/n on the logic board is unfortunately a bit washed out. No s/n, model name or any other info on the case.
I believe that to be just like I mention above, a PVT prototype used for training.

The board does have a serial number which means that board may have been a finalized design, but prior to ROMs being finished.

They worked on the ROMs of the LC well into late September but they were busy making machines to test their production ability prior to that. For training purposes a confidential, non-production ROM would have been just fine I think.

Very interesting. Because the ROMs you have there can be reprogrammed it’s possible they were reprogrammed with RC or GM ROMs, and the sticker remained. Or they intended to replace the ROMs and missed one. Who knows.
 
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