On Thu, 1 Sep 2022, David Barto via cctalk wrote:
If you have a SS/SD drive then yes, punching a notch in the sleeve
would allow you to flip the disk over and use the other side. I’ve done
this in the (very) distant past.
Most drives these days are DS and can R/W the SD disks without
issue, so I wouldn’t expect it to be necessary.
Not quite.
There were TWO issues.
1) many companies distributing pre-written disks for distributing software
did so on "No-Notch" disks that DID NOT HAVE a write enable notch! (They
used a modified drive to do so (such as jumper on 455 drive). That was a
disk with content that "can't be altered". I once had a customer complain
that the disk that I sent him "HAS A VIRUS!". When I got it back from
him, I found that he had punched a write enable notch. But, I also got in
touch with the customer with the disk written prior to his, and the
customer with the disk following his, and confirmed that neither of those
had a virus, and still were no-notch disks. That solidified my decision
to use no-notch disks!
Even if there is a mass mailing of such disks, they can't be written and
repurposed for other use without a modified drive, or punching a write
enable notch. The notch doesn't have to be square, so any old hole punch,
or Swiss Army Knife scissors, can be used.
2) If you have a SS disk, and a SS drive (SD, DD, HD, GCR are IRRELEVANT),
and want to use the OTHER side of the disk (a "flippy"), then you will
need a symmetrical second write enable notch.
AND, if you use a system that uses the index pulse (MOST systems other
than Apple and Commodore) , then you will ALSO need to add symmetrical
index hole access holes. TRS80 was SS SD. PC/5150 was SS DD., until
PC-DOS 1.10/MS-DOS 1.25, when it went to DS DD.
(The "Berkeley Microcomputer Flip Jig" was for marking the positions for
those holes.)
On 8" disks/drives, write enable is by covering over the write protect
notch, if somebody has punched one. But, as Chuck mentioned, that needs
to be with TRULY opaque tape.
And, if anybody from Bill Gates' "Computer Bowl" team is here, that write
enable notch was on the leading (first into the drive) edge of the disk.
If it is a SS disk, and a SS drive, then you will need to add symmetric
index hole access holes.
If it is a SS disk, and a DS drive that does not also have SS index hole
sensors, then you will need to add DS index hole access holes.
(The "Eight Inch Berkeley Microcomputer Flip Jig" was for marking EITHER
set of index hole access holes)
--
Grumpy Ol' Fred [email protected]
