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293Re: Hi & a question

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  • Larry T.
    May 21, 2003
      Actually, most of the controllers for 8" drives that I know were soft
      sector. Only the original MITS and ICOM controllers were for hard
      sector media. And ICOM came out with a later controller that did
      support soft sector floppies.

      As for capacities, the 8" media ran from 128Kb to 1Mb depending on
      density (1x, 2x, 4x) and # of sides (1 or 2).

      The early 5-1/4" drives started at 40Kb and worked their way up. I
      do not recall standard 360Kb on the s-100 systems, that was the
      starting point for the PC. However, Micropolis was the first to
      offer higher capacity drives, they just wern't very reliable and they
      deffinetly we not compatible with other 5-1/4" drives.

      I'll keep looking. If nothing else, I should eventually be able to
      adapt a later Western Digital floppy controller IC to a Tarbell style
      design to get a circuit that will give me the full use of the 1.44Mb
      media. CP/M did not have any problems with media of this capacity so
      it will just be a case of making the boot floppy and boot prom.

      If I find or create something, I'll post data on it back to the group
      for everyones reference.

      --- In altaircomputerclub@yahoogroups.com, alltare <no_reply@y...>
      > Welcome to the group.
      > I haven't heard of any designs for using 3" drives. The Altair
      > software and hardware was all designed around "hard-sectored"
      > diskettes, and that may prove to be the biggest problem. I have
      > never seen a hard-sectored 3" diskette- only soft-sectored.
      > Of course, there were many other S-100 systems that did use soft
      > sectoring, It might be a fairly simple task to do some timing
      > changes on one of those old controllers for use with 3" disks. I
      > don't know the rotational speed of 3" drives, but I think 8" and 5"
      > ran at 360 and 300 RPM. Whatever the speeds, though, you would
      > to compensate for rotational speed differences by making timing
      > changes to the circuits that generate the sector and byte timing.
      > could be full of beans here, but this approach doesn't immediately
      > seem like it would be a major task. What do you other members
      > about this?
      > Done this simply, you wouldn't be able to use the 3" to its full
      > 1.4MB capacity. You would still only use as many tracks as the
      > original system, and as many bytes per track as the original
      > and most likely only one side of each disk. There would be a lot
      > wasted potential, but at least you would be using "state-of-the-
      > diskettes and drives (or maybe not so state-of-the-art. I just
      > that Dell will discontinue installing floppies on most future
      > in favor of CDs). I recall that an 8" floppy back then held 320 to
      > 360 KB on about 80 tracks. I think 5" floppies held about half
      > much data per side on half as many tracks. It's been a long time,
      > so don't take any of my numbers too literally, but I think I'm in
      > right ball park.
      > What I would like to see is a CD burner that could be used in an
      > Altair system, using Altair BASIC, that looked to the system like
      > own hard drive or floppy drive (now THERE'S a waste of space). All
      > of that old software is rotting away on 25 year old diskettes and
      > really needs to be archived on the more permanent CD medium. If
      > ever see anything like that, please tell us about it.
      > I look forward to seeing your pictures.
      > Steve
      > ============================
      > --- In altaircomputerclub@yahoogroups.com, "Larry Troth"
      > wrote:
      > > Hello
      > >
      > > I have just joined the group and I am looking forward to gaining
      > some new
      > > knowledge regarding the old hardware that I have. After 20+
      > in
      > > storage, I will finally be able to get my s-100 systems (yes, I
      > > several) bake in operation. As I get them up I'll post pictures
      > and info.
      > >
      > > My question is about some new hardware for these old systems.
      > While I have
      > > a good supply of 8" floppy drives and floppies, it is only a
      > of time
      > > till the last of them give up the ghost. Has anyone come up with
      > > kit/board/schematic/??? to allow the use of the new 1.44Mb 3-1/2"
      > diskette
      > > drives with these old systems? I would love to transfer my old
      > data from
      > > the 8" media to the 3-1/2" media. Does anyone know of any web
      > pages that
      > > discuss this? Are there any resources out there? (I found a
      > that has
      > > a new card for the SWTP 680 systems to do this, so what about he
      > 100
      > > systems?)
      > >
      > > Larry@u...
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