SCSI Port on 512K w/ 512Ke Upgrade

[Damnathan]

Hi there!

I've got a Macintosh 512K that would seem to be upgraded to a 512Ke (its internal floppy can read 800K disks).

Now, it also has a SCSI port sticking out of the area of the battery compartment, which I am led to believe is probably a Dove MacSnap upgrade, right? Unfortunately I don't have the requisite Torx driver (and I'm also a bit wary of breaking anything), so I haven't cracked the case open.

Now, didn't those upgrades increase the RAM in the machine? When I boot System 6.0.8 (in the "Minimum Software for a Mac Plus" install), the computer reports it has 512K total memory. Could this be?

More importantly, how do I get SCSI support working? When I attach a Hard Disk 20SC (which boots my Mac SE without a hitch) to the battery-compartment SCSI port, it is not recognized by the 512k(e), and certainly won't attempt to boot from it. When I fire up Apple HD SC Setup, it tells me "This program will only work on a Macintosh which has a SCSI connector."

Am I missing an INIT that makes the system recognize the SCSI port? Some other piece of software? Any ideas how I can get the SCSI support working? It would be great to have a hard disk hooked up to the old thing.

Thanks very much!

 

[Mac128]

Now, it also has a SCSI port sticking out of the area of the battery compartment, which I am led to believe is probably a Dove MacSnap upgrade, right?

Not necessarily

Now, didn't those upgrades increase the RAM in the machine? When I boot System 6.0.8 (in the "Minimum Software for a Mac Plus" install), the computer reports it has 512K total memory. Could this be?

Yes, especially if it is a DOVE upgrade, which was an additional and separate upgrade from any RAM or accelerators, which could be used independently. However, if you do have a RAM upgrade or other accelerator, it could have become separated during shipping, especially if it was attached with killy clips.

Am I missing an INIT that makes the system recognize the SCSI port? Some other piece of software?

If it is a Dove MacSnap, then my understanding is there are no drivers needed, it should work identically to the Mac Plus and the SE actual SCSI port.

You need to determine which SCSI card you have. If it is part of a larger accelerator as many were, you may well need an INIT to activate it. So, get that Mac opened. There is a possibility you have an original or REV. 1 ROM, in which case, there is a specific startup sequence, which I don't immediately recall. If a Dove MacSnap, it might have come unseated during shipping, or the ribbon cable is disconnected.

Too many variables to trouble shoot until you know what you have in there.

 

[Damnathan]

Bah. Was afraid you were gonna say that. :-/

Guess I'll have to look into getting a long Torx driver, eh?

 

[Bunsen]

 

[Mac128]

Interesting reading about the 128K ROMs and related System SCSI problems:

http://developer.apple.com/legacy/mac/library/technotes/dv/dv_14.html

According to Apple's troubleshooting guide, if you have the Rev. 1 ROM which most 512Kes had due to the fact they didn't have a SCSI port (so it didn't matter), the SCSI drive must be powered on prior to booting the Mac, but you are probably already doing this.

However, you can eliminate this problem quickly by booting up, and press the rear interrupt switch. A dialog box will pop up with a ">" prompt. Type DM400000 and press the return key. The Hex dump in the top row, 2nd & third columns will tell you which REV ROM you have:

4D1E EExx = orig.

4D1E EAxx = Rev. 1

4D1F 81xx = Rev. 2

If you have the last one, then you can rule out the ROM involvement in the problem.

 

[Damnathan]

Ah, I was worried maybe I had the wrong ROM. Thanks for the hex dump tip! Have determined that I have the late-model ROM, so everything's tickety-boo there.

Would you believe I don't have any BiC ballpoints in the house? I've got Stabilo point 88s coming out my ears, but no cheap-o pens. I always knew my pen snobbery would be my downfall one day.

Ah well. I'll either go buy some or look online for an appropriate 'driver and report when I have the patient opened up.

Thanks for your help!

 

[Bunsen]

The trick is getting one long enough, and narrow enough, to reach into the rear screw holes. I've always had my doubts about the Bic pen hack myself - I don't reckon that plastic would stand up to much torque in the case of a stuck screw. My version uses a 6" length of copper tube, crimped around the drivers at each end.