Kaypro System disks? - test-drb@ccmp.vtda.org

2 Jul 2009

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Subject: Re: Kaypro System disks?
   From: Fred Cisin <cisin at xenosoft.com>
   Date: Thu, 02 Jul 2009 17:47:38 -0700 (PDT)
     To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>

  Will a Kaypro really play nice with a
 3.5" floppy drive? It never occurred to me to try it. I
 thought the floppy drivers under CP/M only knew about DD
 drives, and the bios on the boot disk was different between
 the various Kaypro models among other things to support the
 different floppies they had (SS/SD, SS/DD, DS/DD). 
A 720K 3.5" IS a DD drive.
Depending on the specific model, the Kaypro will only see 40 tracks of the
3.5", and may or may not support using the second side. 
depends on the model and if it has one of the improved BIOS chips like 
Advent Turbo rom.

I have a 4/84 with turborom, disk personality card and 1MB Ramdisk
and it've very nice with four drives.  One is 40track 2sided, the other 
two are fitted to the other half height slot and are two 3.5" floppies at
720k/781k as there are a few formats that get a bit more on a disk.  
The forth is tucked inside and used to hold stuff I always need.

Note: the drives used are older Sony 720/1.44m drives with unit select 
switches.

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 There was substantial third party support (Advent?
Micro Cornucopia, etc.)
for DS 80 track ("720K") drives on Kaypros. 
Advent was one I know well.  I've seen others on line fairly recently.

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 One quirk about the Kaypro format, is that it puts an
incorrect value in
the head number field of the sectors on the second side.  But, it doesn't
seem to object to a disk having the correct value there. 
Head selection is not by the FDC (1793) but by a port.  The FDC for side 2
is programmed as if it were side 1.  A bit odd but there are worse.

Allison

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Grumpy Ol' Fred     		cisin at xenosoft.com 