[geeks] floppy disks

[Geoffrey S. Mendelson]

Depending upon what you need them for, you may be able to get used ones
from freecycle and similar lists. Many people still have them and
no longer have the computers they "belong to".

Another option for "low" density 3.5 inch disks (720k/800k) is to cover
both sides of the density hole with opaque tape. Some drives check with
a switch, some with a photocell. Some early drives don't check at all.

The magnetic material is close enough between the types to work for
reasonable amounts of time. I've had ones that were several years old
which still were usable after storage.

I also try to make images of disks and save the images.

Almost everyone used MFM type data encoding, except Apple and most
of the 8 bit "home computers"( Atari, Commodore). Apple switched to
MFM encoding with the 1.4m disks, Commodore with the Amiga and
Atari with the "ST". MFM disks can be read (and sometimes written)
with a standard PC.

There is a freeware program called OMNIFLOP which will read and write
floppies from hundreds of systems. For many of them it will make images
and copy files to/from them. It does not do data format conversion,
so you must still have a program to read those documents. :-)

As I was collecting Macintosh disks. I made images of things like
system disks, etc using "dd". This only works for 1.4m disks, but
the images can now be written using a *NIX system or using a Linux
utility RAWWRITE, under Windows. 

One mistake I made was making backup copies of the disks for my AT&T 3b2
systems. (SyS V, R3.2). I used a program called Teledisk for the PC which
was freeware/shareware and read 720k disks on a 1.2m drive. Unfortunately,
the image file format was unique and never documented. The program can
still be found on PC sharware disks from the era, but it won't run on
anything modern. 

It does not matter to me very much as not only don't I have anything
to run Teledisk on, I don't have (and as long as I live outside the U.S.)
won't have a chance of even beeing in the same building as a 3b2.

I also never got to work two things I tried, but it may have been either
the hardware, or the famous "ID ten T" error. One was SCSI, the other
was a 3.5 inch floppy drive.

As a trick of memory, I can't tell you what I had for breakfast yesterday,
but I can tell you the hidden password for the diagnostics and hard disk 
intialization floppy was "MCP". :-)

BTW, I still have a copy of a program called something like Media Master
which read CP/M floppies on a PC and the PC DOS version of Wordstar 3.3,
which will read Wordstar documents from all of those CP/M computers.

As a triva point, it was written in 8080 assembler and translated to
8008 assembler using Intel's conversion program. Wordstar did not
even fix the bugs in the CP/M version they started with and the process
created a few of its  own.

I seem to have lost my copy of "A WordStar User's Guide to Word Perfect"
by W. S. Begone and W. P. Forever published by the WordPerfect Corporation,
but I still have WordPerfect 4.2 and 5.1.

Geoff.

-- 
Geoffrey S. Mendelson, Jerusalem, Israel gsm at mendelson.com  N3OWJ/4X1GM
IL Voice: (07)-7424-1667  Fax ONLY: 972-2-648-1443 U.S. Voice: 1-215-821-1838 
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