gonzalez@bbn.com (Jim Gonzalez) (04/10/90)
In my brief email exchange with Wayne Hortensius, he mentioned that he'd succeeded in using AT-style 1.2Meg 5.25" drives on a Cromemco Z2H as an 8" drive. I've had no luck in reaching him via email, so I never learned the details of his work. It has since occurred to me that one might be able to do the same thing with 3.5" drives. In fact, I thought someone had told me that they'd done it. Has anyone on the net used a 3.5" drive on an 8" controller? What did it involve, besides some cabling? Any caveats? -Jim.
grege@gold.GVG.TEK.COM (Gregory Ebert) (04/10/90)
I have looked into putting a 3.5" on my 8" controller, and the only differences I could find are (1) the MOTOR_ON signal for the 3.5" drive -- it can be tied to DRIVE_SELx on the 8" drive, and (2) the 3.5" drive has seperate signals for DIRECTION and SIDE_SELECT, whereas the 8" drive 'muxes' them. The data rates are identical. You will need to tweak the stepper rate for the head. There is (was ?) a 5.25" drive by Mitsubishi which is (was?) electrically interchangeable with a 8" DSDD drive. It could store up to 1.6MB formatted. Unfortunately, having just moved, gotten a new job, and being a new first-time daddy, I haven't had time to _actually_ do it yet. As soon as the &^%#@&$ doctor bills are paid, I'll snag a drive and try it.
jensting@skinfaxe.diku.dk (Jens Tingleff) (04/10/90)
gonzalez@bbn.com (Jim Gonzalez) writes: [..] >done it. Has anyone on the net used a 3.5" drive on an 8" controller? >What did it involve, besides some cabling? Any caveats? Close, I use an 8" drive on a 5.25" controller (both running as high density, i.e. 1.2 MB). The difference that I know of, is that 3.5" drives use different pull-up resistors (1 KOhm for 3.5", 300Ohm for 8" ??). This means that you might not get away with quite the same length of cable.. . Other than that, it should be a breeze (given that you can figure out the settings of the dip-switches). Jens jensting@diku.dk is Jens Tingleff MSc EE, Research Assistent at DIKU Institute of Computer Science, Copenhagen University Snail mail: DIKU Universitetsparken 1 DK2100 KBH O
koziarz@halibut.nosc.mil (Walter A. Koziarz) (04/11/90)
In article <1990Apr10.062350.29895@diku.dk> jensting@skinfaxe.diku.dk (Jens Tingleff) writes: > >The difference that I know of, is that 3.5" drives use different >pull-up resistors (1 KOhm for 3.5", 300Ohm for 8" ??). This means that >you might not get away with quite the same length of cable.. . >Other than that, it should be a breeze (given that you can figure out the >settings of the dip-switches). > > Jens > I would be incredibly grateful if anyone having success at this e-mail me some insight. I am having a devil of a time dealing with timing. The 3.5s rotate at 300 rpm and the 8s (and 5.25 hds) rotate at 360rpm. My system is a Zenith Z-100 and I'm using a stock Z-207 floppy (5.25 & 8) controller. Many thanks!!! Walt K.
CUMMINGS@S55.Prime.COM (Kevin J. Cummings) (04/11/90)
A long time ago (years) California Digital (a clearing house for dis-continued
products and bargins) sold a 5.25" disk drive that they claimed was an 8"
drive electrically. I assumed that this means that it had the same electrical
interface (did that mean the same edge card connector wired the same way) as
an 8" drive did. I remember that the 8" drives used a 50 pin daisy chained
cable, while the 5.25" drives used a 34 pin cable (basically the same signals,
a few were different, in different places on the cable. I'm running 720K
3.5" drives on the same cable as my 40 and 80 track 5.25' drives (using the
same disk controller). I have nothing on my 8" controller (never bought
any 8" drives B^). I always wondered if I could add a HD 5.25 1.2MB drive
on the 8" controller? My 1.2MB drive on my IBM-compatible PC is hooked to
the same 34 pin connector as my 720K 3.5" drive. That sorta says no. Anyone
successfully run a 1.2MB drive on an 8" controller?
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============================================================================Azog-Thoth@cup.portal.com (William Thomas Daugustine) (04/11/90)
If you arent afraid of calling long distance (whereever you happen to be!) try calling Holly Park (201)757-1491. A fellow there has succeeded in installing 3.5" flops on a Xerox with originally 8" flops. From what I gather, this does NOT worl on a DEM-II unit. No longer having a Xerox 820-II, I unfortunatly cant attempt this project. Also, seems to require reburning ROMs, so the machine will know the new allocations for the drives. Billy D'Augustine Azog-Thoth@cup.portal.com
wieland@ea.ecn.purdue.edu (Jeffrey J Wieland) (04/11/90)
How about putting 3.5" drives on a machine that expects 5.25", 96 tpi drives? My TurboROM-equipped Kaypro can handle the 5.25 96 tpi drives - are the 3.5" drives the same electrically? I know that I would need to get an adapter to plug the drive into a regular floppy drive cable. -- Jeff Wieland wieland@ecn.purdue.edu
bill@flash.UUCP (William Swan) (04/12/90)
In article <9004110707.AA07305@ucbvax.Berkeley.EDU> CUMMINGS@S55.Prime.COM (Kevin J. Cummings) writes: }A long time ago (years) California Digital (a clearing house for dis-continued }products and bargins) sold a 5.25" disk drive that they claimed was an 8" }drive electrically. I assumed that this means that it had the same electrical }interface (did that mean the same edge card connector wired the same way) as }an 8" drive did. I remember that the 8" drives used a 50 pin daisy chained }cable, while the 5.25" drives used a 34 pin cable [...] }Anyone successfully run a 1.2MB drive on an 8" controller? Not that this will help you, but yes. In late '82 or early '83 as an Alspa Computer, as an experiment, hooked a recently announced (Mitsubishi?) 5-1/4" drive up to one of their engineering systems, in place of the 1.2MB Tandons they normally used. As I recall it had the 50 pin connector. It worked just fine, but the company didn't go ahead with it as a product because there was no standard for 5-1/4" high-density formats, whereas for 8" there was always SS/SD. -- Bill Swan bill@Summation.WA.COM Send postal address for info: Innocent but in prison in Washington State for 13.5 years (or more): Ms. Debbie Runyan: incarcerated 01/1989, scheduled release 07/2002. In now: 1 year, 2 months, 3 weeks, 1 day.
rlb@cs.odu.edu (Robert L. Bailey) (04/12/90)
In article <9004110707.AA07305@ucbvax.Berkeley.EDU> CUMMINGS@S55.Prime.COM (Kevin J. Cummings) writes: >A long time ago (years) California Digital (a clearing house for dis-continued >products and bargins) sold a 5.25" disk drive that they claimed was an 8" >drive electrically. I assumed that this means that it had the same electrical >interface (did that mean the same edge card connector wired the same way) as >an 8" drive did. I remember that the 8" drives used a 50 pin daisy chained >cable, while the 5.25" drives used a 34 pin cable (basically the same signals, >a few were different, in different places on the cable. I'm running 720K >3.5" drives on the same cable as my 40 and 80 track 5.25' drives (using the >same disk controller). I have nothing on my 8" controller (never bought >any 8" drives B^). I always wondered if I could add a HD 5.25 1.2MB drive >on the 8" controller? My 1.2MB drive on my IBM-compatible PC is hooked to >the same 34 pin connector as my 720K 3.5" drive. That sorta says no. Anyone >successfully run a 1.2MB drive on an 8" controller? I would think that it should be possible to do just that. Years ago, I was putting together a Xerox 820-I and I installed both an 8" SSSD and 3 5 1/4" drives all daisy chained off the same cable. The trick that I used was this: I too, noted that the 50 pin 8" connector and the 34 pin 5 1/4" connector carried the same signals on the same sides, but, they were located at different pin numbers. My solution was to use a 34 pin connector but I used a small saw to cut the connectors slot so that there were no longer any stops on the ends of the connector. (The "stops" as I refer to them are the ends that keep the connector contact #1 aligned with the board contact #1) By removing these, I could then position the 34 pin connector (by offseting it from pin #1) so that the proper signals were connected to the proper pins of the 8" drive connector. I don't have the info handy, but I beleive that I also, had to put a jumper wire on the 8" drive so that the motor on line was activated at the same time as the drive select line. Other than that, I don't beleive that I had to do anything special to make things work. Your problem is the reverse of mine, but, I don't see any reason why it couldn't be done as long as you get the signals to the right pins! Bob Bailey (rlb@cs.odu.edu)
koziarz@halibut.nosc.mil (Walter A. Koziarz) (04/13/90)
In article <9004110707.AA07305@ucbvax.Berkeley.EDU> CUMMINGS@S55.Prime.COM (Kevin J. Cummings) writes: >the same 34 pin connector as my 720K 3.5" drive. That sorta says no. Anyone >successfully run a 1.2MB drive on an 8" controller? > Yup, I had to put a sort piece of cable between the 50 pin and 34 pin connectors to slightly re-arrainge the signals. It definitely works. The 5.25 hi-density 1.2M drive can indeed be considered electrically equivalent to an 8 inch. Walt K.