a few 128k questions

[Peter.Howard]

guys I have a few questions I been searching for the answers to these can anyone help?

Looking at heaps of different pictures online, ebay of 128k's for sale, some seem to have a grey surround to the Apple logo on the front of the case, while others match the overall colour of the computer, is there any significance to this?

I understand the 128 and 512 have a 64kb ROM, was there only one version of this ROM, if there were different revisions is there any way, visual or otherwise on how to spot them?

EDIT; oh and is there any good books I should purschase, to read up on these computers, that might answer all my questions?

thank you.

 

[Dennis Nedry]

[...]some seem to have a grey surround to the Apple logo on the front of the case, while others match the overall colour of the computer, is there any significance to this?

All Mac 128ks have their Apple logo on a square piece of formed and painted aluminum that is stuck into a corresponding recess in the case. The Mac's plastic has a texture, whereas the Apple logo is smooth. It could be that a camera flash lights up the square differently than the rest of the Mac. That's all I can think of.

I understand the 128 and 512 have a 64kb ROM, was there only one version of this ROM, if there were different revisions is there any way, visual or otherwise on how to spot them?

My records indicate that there are 2 different 128k/512k Mac ROM checksums:

0x28BA61CE

0x28BA4E50

One way to check is to use a Mac ROM dumper, such as GetROM, to save the Mac's ROM to a file. Then open it in a hex editor. The first 4 bytes of hex data is where the checksum is stored.

I'm not aware of any practical difference between these ROMs, and given that the checksums are so similar, it stands to reason that only a very small number of bytes were changed. There isn't, for example, an extra driver present, but there may be some little bug fixes here and there.

 

[Mac128]

342-0220/21-A/B clearly printed on the ROM with a respective 1983/1984 copyright date.

The new ROM addresses a revised stepper motor in the 400K Sony drives. Newer drives are incompatible with the older ROMs, a fact with which one must be aware when swapping out 400K drives with 64K ROMs.

Addressed in this topic:

viewtopic.php?f=7&t=11687

And I agree with Dennis re: camera lighting. All Mac 128K & 512K/es have front badges with beige backgrounds which exactly match the color of the case. All rear case badge's background color are the darker olive accent color. There are no exceptions to this, and was consistent all the way through the last 512Ke manufactured even after the case switched to Platinum. So it is either lighting, or someone has switched them around, or they have discolored with age, or appear gray compared to the discolored case.

And no, there is not one good reference book which will have all of your answers. Most of this knowledge comes from direct experience, and tidbits gleaned from Apple's TIL, and numerous books, and photos from period literature, BBS and usenet archives.