pld@au-bon-pain.jj.lcs.mit.edu (Peter L. DeWolf) (07/20/90)
I own a perfectly good Mac II internal hard disk. I am considering
buying a newer, bigger, faster, better hard disk. I seem to have four
options.
1) Buy a new external drive.
2) Install the new internal drive in the Mac II case and get rid of
the old one.
3) Install the new internal drive in the Mac II case and convert the
old one into an external drive.
4) Figure out how to install two internal drives in the Mac II case.
Option 1 is easy.
I'd like to reject option 2; you can never have too much disk storage.
Option 3 should be possible, but I don't know what is involved. What
is provided in an external drive that is missing from an internal
drive? A case, cables, a power supply, etc. Does anybody supply a
"kit" or such that would make this easy?
Is option 4 possible? With the right mounting brackets, you could
probably physically mount certain combinations of drives. How would
you electrically connect both of them to power and the SCSI bus?
Again, are there any "kits" or such available to do this?
Thanks much.
Peter L. DeWolf
Motorola Cambridge Research Center
pld@mcrc.mot.com -or- pld@abp.lcs.mit.edumidkiff@portia.Stanford.EDU (Neil Midkiff) (07/20/90)
In article <PLD.90Jul19142800@au-bon-pain.jj.lcs.mit.edu> pld@au-bon-pain.jj.lcs.mit.edu (Peter L. DeWolf) writes: >I own a perfectly good Mac II internal hard disk. I am considering >buying a newer, bigger, faster, better hard disk. I seem to have four >options.... > 3) Install the new internal drive in the Mac II case and convert the > old one into an external drive. >Option 3 should be possible, but I don't know what is involved. What >is provided in an external drive that is missing from an internal >drive? A case, cables, a power supply, etc. Does anybody supply a >"kit" or such that would make this easy? > {4) Both inside} >Is option 4 possible? With the right mounting brackets, you could >probably physically mount certain combinations of drives. How would >you electrically connect both of them to power and the SCSI bus? >Again, are there any "kits" or such available to do this? I'm doing the same thing and have a temporary hookup working. I couldn't find room inside the IIfx for a second HD; I first thought that it would fit where the second floppy would go but the space needs to be about 1/4" higher. So I have a kluge of option 3 and 4 together...electrically the second HD is on the internal SCSI bus, but its ribbon cable is just going out of a slot access hole in the back, and it's now sitting "naked" (well, in a mounting bracket) on top of the IIfx. Here's what I did: (This is for Quantum drives, by the way...I don't know if any details will differ with others.) I got a ribbon cable about 16" long, 50 conductors, with female 50-pin connectors (2 rows of 25 on 0.1" centers) at each end. This was a surplus item at a local parts dealer. I bought a 50-pin male insulation-displacement connector and mounted it 1" from one end. The Mac's internal connector plugs into this male connector, the nearby female connector goes into the internal HD, and the long end goes out the hole in the back to the external HD. ***WARNING: If you have any doubt in your mind about how to make sure that pin 1 connects to pin 1 which connects to pin 1, and so forth, DON'T TRY THIS AT HOME! It's easy to do this right if you're familiar with cables; it's easy to do it *wrong* if you're not.*** I removed the termination resistors from the internal HD. On the Quantums these are three 9-pin single-inline-packages (SIPs) marked RN201-203 immediately adjacent to the 50-pin SCSI connector. They are in sockets, so they just pull out. Make sure your external HD has them! And if you transfer them from one to the other, keep the right orientation: the end marked with a dot or a bar is the "common" terminal and the other eight pins are electrically the other ends of eight resistors. If you get them backwards it won't work. I bought a "Y"-connector for the disk drive power, and spliced extra wire (actually four wires, each about 14 inches) into one leg so that it would be long enough to reach out the back. I've seen these "Y" connectors at several electronic outlets; they seem to be a fairly standard item, but they come with only about four inches of wire between the central male connector and each leg's female connector. I didn't worry about the power supply because I have only one slot out of six filled. The bottom line is, IT WORKS! ---------------- Now for the real experts, some questions: Sometimes the external disk doesn't automatically mount when I start up. It can always be mounted with a shareware cdev which scans the SCSI bus and tells you what's on it, or lets you mount. But why does it usually NOT mount at startup? How much power does a 3.5" Quantum HD use? Is orientation (flat, edge-up, or whatever) important to proper operation? You see, I'm esthetically dissatisfied with this hookup, and want to incorporate it into an external case. So far I've seen a case that is intended for two half-height 5.25" floppy drives that I can get cheap. It has a crude power supply inside, but it would be good enough if the current required is not too great. It also has space for a fan, which some external drive cases include. Its shape, however, would require the drive to be sitting on one of its long edges. Of course, for an external HD, you need to use 50-pin "Centronics" or "Amphenol" style connectors, like the old multi-line telephone plugs. You'll have to get a 25-pin to 50-pin SCSI cable to use with the Mac's back SCSI jack, unless you're daisy-chaining onto another SCSI device. And so forth... Enough already! -Neil P.S. If you find a source for a "kit" let me know! I don't have too much invested in this kluge, so could junk it for a better solution.