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IIci ROM Rating
- Thread starter Phipli
- Start date
I definitely can't answer definitively, but thought I would share a few clues since your question piqued my curiosity.
I attached a pic of the stock mask ROM chips that came off my IIci. Yup, they mixed and matched ROM vendors on the same board. The Sharp ones don't provide any extra identifying info on top of Apple's part number other than a date code, but the Toshiba one does. The TC531001CP has a datasheet available online.
According to the datasheet it would really be a part number of TC531001CP-12 or TC531001CP-15 for 120ns or 150ns. Sadly the speed part of the marking doesn't seem obviously marked on the chips, but I would assume it's one of those two speeds? I guess it doesn't necessarily prove anything because there could have been other speeds available that weren't part of that particular datasheet.
This site has a pic of a IIci logic board that has all Toshiba ROMs and it looks like F739, F740, F741, and F742 are the Toshiba codes for the four Apple mask ROMs. At first I was thinking maybe the F stands for 15, but if you search Google Images you find several other first letters like E, P, and R -- so I don't think that's it. I did find one image of a chip that had -12 marked separately from the extra 4 digit code, for what it's worth.
Guide to the Macintosh Family Hardware 2nd Edition says that the IIci's ROM access rate is 20.0 MB/s on page 231 (page 270 of the PDF). I remember reading this a while ago and couldn't figure out exactly how to decipher that. I would assume it means 5 MB/s per chip, which works out to an access rate of 1/5242880 seconds per access, or 190 ns per access? I'm not sure exactly how that quoted access rate ties in with chip ratings though.
I attached a pic of the stock mask ROM chips that came off my IIci. Yup, they mixed and matched ROM vendors on the same board. The Sharp ones don't provide any extra identifying info on top of Apple's part number other than a date code, but the Toshiba one does. The TC531001CP has a datasheet available online.
According to the datasheet it would really be a part number of TC531001CP-12 or TC531001CP-15 for 120ns or 150ns. Sadly the speed part of the marking doesn't seem obviously marked on the chips, but I would assume it's one of those two speeds? I guess it doesn't necessarily prove anything because there could have been other speeds available that weren't part of that particular datasheet.
This site has a pic of a IIci logic board that has all Toshiba ROMs and it looks like F739, F740, F741, and F742 are the Toshiba codes for the four Apple mask ROMs. At first I was thinking maybe the F stands for 15, but if you search Google Images you find several other first letters like E, P, and R -- so I don't think that's it. I did find one image of a chip that had -12 marked separately from the extra 4 digit code, for what it's worth.
Guide to the Macintosh Family Hardware 2nd Edition says that the IIci's ROM access rate is 20.0 MB/s on page 231 (page 270 of the PDF). I remember reading this a while ago and couldn't figure out exactly how to decipher that. I would assume it means 5 MB/s per chip, which works out to an access rate of 1/5242880 seconds per access, or 190 ns per access? I'm not sure exactly how that quoted access rate ties in with chip ratings though.
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Yup, double checking I get that would be 191ns per access I think. I suspect you've answered my question.
I anticipate they're 200ns parts.
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