Is this really possible?

[LCGuy]

This morning I was reading Tom Lee's Classic Mac Repair Notes, and he says that apparently you can use a SuperDrive in a pre-SuperDrive Mac, but it will behave as an 800k drive. I have a SuperDrive in my Quadra 700 that I don't really need, so I'm thinking..maybe I could remove it, and stick it in my Macintosh (upgraded to 512ke status with 512ke/Plus ROMs), and get it going again, as I don't have a working 800k drive for it.

So, would this really work as intended? I know that Tom Lee knows what he's doing with the Classic Macs...just that I thought I'd read warnings before of bad things happening if you connect a SuperDrive to a pre-SuperDrive Mac.

 

[tomlee59]

The only problem you might encounter is related to the ribbon cable. Some superdrives will behave badly if pin 9 is connected, and if the -12V supply is connected. Other than those considerations, you should be fine electrically.

 

[LCGuy]

Excellent, thanks. Just that I thought I'd heard warnings before of frying the drive or IWM chip, thats all.

 

[tomlee59]

I think the dire warnings apply to hooking up an Apple II 5.25" drive to a Mac. That combination apparently will usually cook either the drive or the IWM chip, or both.

As for your situation, again, the most serious problem you might encounter is related to feeding -12V to the superdrive. Some models have no connection there, so there isn't a problem. However, drives from some later runs reused this pin for other purposes. Connecting -12 to this pin causes the eject motor to spin continuously, and may damage something if connected too long. I've never had this happen to me, but maybe that's because I immediately shut things down as soon as I hear it go on.

 

[OtakuMegane]

I guess the only risk is the -12V line and you will know if it's causing a problem before any damage is done if it reacts by making the motor run constantly. I used a superdrive in a Plus for a while and had no problems, functioned just like a normal 800k drive.

 

[Scott Baret]

Especially useful to know if you come across a SuperDrive made in mid-1992 or later, their eject mechanisms rarely if ever gummed (and these drives were still the auto-inject type; read my article on LEM about drives for more details).

 

[Mac128]

Also, there are some detailed instructions here for modifying the internal ribbon cable, the first listing under "Problems" (pictures to come, sorry):

http://mac128.com/800k.html

Scott, I did a search for your name and superdrive on LEM and got several articles but none that refer to using the drives with an IWM. I did find an article about auto-inject vs. manual Superdrives, but it was attributed to another author: http://lowendmac.com/macdan/md07/0926.html

Care to provide the correct link? Thanks!

 

[LCGuy]

Little update - I dropped the SuperDrive into my Apple 3.5 drive enclosure, works fine. Now to modify that cable...thanks everyone

Edit - To err is to be human

 

[Mac128]

Little update - I dropped the SuperDrive into my Apple 5.25" drive enclosure, works fine. Now to modify that cable...thanks everyone

No need to modify the internal cable when used externally. If it works fine in a 5.25 then you needn't do anything else. The cable modification is mainly for the internal 20-pin connector. That's fascinating it works with a 5.25 enclosure on a Mac. Thanks for trying that out!

 

[LCGuy]

err, oops, I just realised, I mean 3.5" enclosure, NOT 5.25"! I repeat, I have NOT connected any 5.25" drive or enclosure to ANY Macintosh, I simply made a typo.

And the reason I'm modifying the cable is that I'm installing the drive internally.

 

[tomlee59]

I'm glad that it works, and that no magic smoke was liberated.

 

[LCGuy]

As am I. I'm just hoping at the moment that nobody goes and connects a 5.25" drive to their poor Mac after my stupid typo. :-/

 

[Mac128]

LCGuy, I wouldn't worry too much. Actually I think there's a good case to be made that it would work if the Apple 5.25 uses the same 20 pin drive header connector. Fortunately on the DB-19 connectors, Apple standardized the pinouts pretty closely between platforms. All the voltages match properly, so there's no chance of frying anything by a voltage going into a circuit path not intended for one. The UniDisk & 3.5 have interface boards, but I don't know about the FDHD/Superdrive, I would assume that to be the case if it still supports passthrough, but perhaps that circuity's not necessary with a single drive?

 

[LCGuy]

Erm, Apple 5.25" drives will not work with any Macintosh, if you try it, you will fry your IWM chip. Thats why I freaked when I realised I made a typo - I don't want anyone going and plugging their 5.25" drives into their Macs and frying their IWM chips!

For the record, I had a look at it this morning - the wires are cut, the drive is in, and it all works, I can even play Carmen Sandiego :beige:

 

[Mac128]

No No LCGuy, you said you put your SuperDrive in your 5.25 drive case. If anyone read it, that's what they would have thought you did. Based on the cable pinouts, all the circuits should go to the right place as long as the 20 pin header connection is the same pin configuration as in 3.5 drive headers. Or you might just as well have used a spare external 3.5 disk cable lying around. It should all work. From my perspective there's no reason you couldn't put a 3.5 drive in a 5.25 case. If you are concerned about the 5.25 comment, that's what edit is for. Let's just agree to remove all remarks to 5.25 and no one will be the wiser ;-)