Kaypro System disks?

Fred Cisin cisin at xenosoft.com
Tue Jul 7 14:56:29 CDT 2009

> On 7 Jul 2009 at 17:33, feldman.r at comcast.net wrote:
> > <quote>Both the Kaypro 2x,4,10 (DSDD) and Zorba 40 trk (DSDD) formats
> > have a peculiarity that prevents you from using a disk that is created
> > on the "native" computer.  In both cases, the only way to transfer
> > files is to first format a transfer disk in the Kaypro or Zorba format
> > using MEDIA MASTER and your computer.  Then use the Kaypro or Zorba
> > computer to transfer files from the "native" disks to the disk you
> > created with MEDIA MASTER.  Then using MEDIA MASTER, you can transfer
> > the files to any format you wish.

I think that the problem that he is referring to is the invalid head
number in the sector headers on the second side.  It's ignored by WD179x,
but requires going below INT13h on PC.

On Tue, 7 Jul 2009, Chuck Guzis wrote:
> Well, yes and no.  The Kaypro formats, at least in its non-Advent ROM
> incarnations, 10 512-byte sectors per track, leaving out the IDAM on
> each track.  The NEC 765 and its derivatives go blind for a period
> after the index (the original 765 and 8272 are blind for longer than
> the later versions of the chip) long enough to avoid seeing the IDAM.
> The problem with the Kaypro is that there is no IDAM on Kaypro-
> formatted diskettes, so the IAM of the first sector isn't seen and
> only 9 sectors instead of 10 are visible to the 765.
> There are several ways around this.  One, as mentioned, is to format
> the Kaypro diskette on the PC and write files to it, but that assumes
> that you still have the Kaypro around to write the files.  Another
> commonly used method is to tweak the spindle speed a bit slower so
> that the first sector IAM just slips past the "window".  Another is
> to isolate/disconnect the INDEX/ signal from the floppy drive so that
> it isn't seen at all and the 765 always has its eyes open.

A small piece of opaque tape (write protect tab) over the index hole will
get around it, but then most errors are mis-reported as 80h ("Not ready")

> Finally, one can replace the uPD765 with a uPD7265, which leaves out
> the IDAM nonsense and Kaypro disks will read just fine.

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