It is even possible to make a disk that is readable as multiple disk
formats, so long as each is expecting the DIRectory tracks to be in
different places.
On Sun, 20 Sep 2015, tony duell wrote:
So when used under OS-9 it acts normally (directory where the OS expects to
find it), just with
this apparently useless file. Ditto under Color TRS-DOS.
Exactly.
Trying to combine Coco, TRS80 model 1, and Apple][, would require track
17 to have MFM, FM, and GCR sectors/encoding.
BUT, many CP/M formats had different number of "reserved tracks" (how many
tracks the DIRectory was from the beginning of the disk). A good handful
of those could be mixed.
There were several reasons why there was never a STANDARD 5.25" CP/M
format. I once had the opportunity to ask Gary Kildall what the standard
would be for 5.25". He replied, "8 inch single sided single density". I
repeated, "Yes, but waht about 5.25"? He repeated, "8 inch single sided
single density". I understood, but was not much enlightened.
A rare few vendors actually WANTED their disks to be inaccessible by
others! At NCC 84? (the one in Anaheim, where a couple of people died
from the heat in the tents), I asked Intertec (Superbrain) and Televideo
about their disk formats. They both, and only them out of all
manufacturers that I asked, asserted that the only possible reason to read
their disks with another machine was to pirate their proprietary software!
(So, I added those formats that night in my hotel room).
Dysan (remember them?) thought that they had a solution. When
"shirt-pocket" disks were on the horizon, there was much debate about 3" V
3.5" V 3.25". Dysan was pushing the 3.25" size, because other than a
solid hub, it was the same as a conventional floppy, and would require
much less retooling. They set standard format(s) for 3.25". Then to make
absolutely sure that it would get adopted, they bet the company, and set
up a software distribution company! Most major software products were
available on 3.25"!! I eventually ended up with some of the
drives and disks from Micropro (WORDSTAR). But then, Amstrad,
Gavilan, etc. went with 3". Apple and HP went with 3.5", and the battle
was over. In spite of the impressive library of available software, as
near as I can find out, the Seequa Chameleon 325 was the ONLY machine to
reach market with 3.25" drives.
George Morrow said that standards are wonderful, that everybody should
have a unique one of their own.
