Cromemco 4FDC, How do you format a disk?

From: Don Maslin <>
Date: Thu Jul 29 00:40:25 1999

On Wed, 28 Jul 1999, Fred Cisin (XenoSoft) wrote:

> > I nearly did. It was just that I couldn't find a spare 3.5" drive when I
> > had the M4 in bits. One day I'll come across one. I don't use 3.5" disks
> > much, apart from on the PCs. The other machines have 'real' disk drives :-)
> > I am also a great believer in making measurements rather than just trying
> > it (which seems, alas, to be the modern thing to do). What if it works. I
> > don't know if the pulse rate really is similar, or if I was just lucky
> > and the drive could handle a strange data rate. By making the
> > measurement, I know what is going on.
> My understanding back when the 720K 3.5 was being develeoped was that it
> was INTENDED to be fully interchangeable with the 5.25". Therefore, it
> "should" be OK, if the design spec for full interchange was adhered to..
> BUT, there's always the possibility that "because NOBODY EVER uses FM
> anymore,..." that they could have cut some corners that might interfere
> with something that is still nominally part of the spec. That, of course,
> could differ from one brand of drive to another.
> > I believe the 3.5" drive will work as well. That's what this discussion
> > is about. If it doesn't, I will have to investigate why not, since all
> > the measurements I've made so far say that it will.
> > > But then there are the INTERESTING ones:
> > Most PC controllers keep the drive turning at 360rpm and use the 300kbps
> > data rate.
> MOST. I was surprised the first time that I encountered the dual speed.
> > > Weltec 1.2 XT: To handle 1.2M diskettes in PC/XT, which only supported a
> > > 250K data transfer rate, Weltec made a 1.2M drive that ran at 150 RPM!
> > 150rpm? Surely it should be 180rpm (== half the 360rpm of a normal 1.2M
> > disk with the 500kbps data rate).
> That's right. 180RPM. Sorry.
> > That's one I've never seen....
> I don't think that it was around for long.
> Other oddballs:
> Tandon TM100-4M: 100TPI, instead of 96. I think that the M may have
> stood for "Micropolis", who were the early 100TPI.
> 3": common in some circles
> 3.25": Dysan bet the company on soft-sided floppies. Has anyone ever
> seen one in anything other than a Seequa Chameleon 325? Anyone ever seen
> the 325? Anyone need some used blank floppies? I might even still have
> an alignment disk or 2.
> 67.5TPI (40 track) 3.5": used for the Epson Geneva PX-8
> Anyone know what the RS M100 "Portable disk drive" FIRST model used? Was
> it FM?
> 2.8 M Barrium Ferrite:
> "Floptical":
> "LS-120":
> Drivetec/Kodak:
> Amlyn: weirdest drive that I've got. Somewhat deeper than usual full
> height 5.25, sticking out quite a bit. Used a holder holding 5 600
> Oerstedt diskettes, with disk changing under software control, for a total
> of 6M. Was marketed for PC/XT, so it had it's own controller. Supposedly
> used analog positioning, and could handle 48, 96 and 100 TPI! I'll
> believe that if/when I can finally get around to checking it out.

Or how about whatever fit the Canon CMD 500 SS drive that used a floppy
approximately 4" wide? I have two of the drives, no disks, and no idea
as to what they were used in!

                                                 - don

> --
> Fred Cisin
> XenoSoft
    Don Maslin - Keeper of the Dina-SIG CP/M System Disk Archives
         Chairman, Dina-SIG of the San Diego Computer Society
       Clinging tenaciously to the trailing edge of technology.
     Sysop - Elephant's Graveyard (CP/M) Z-Node 9 - 858-454-8412
        see old system support at
visit the "Unofficial" CP/M Web site at
            with Mirror at
Received on Thu Jul 29 1999 - 00:40:25 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:32:14 BST