19 Jan
2023
19 Jan
'23
7:13 p.m.
On Fri, 20 Jan 2023, Chris via cctalk wrote:
Ok. So it's ultimately superior to using s/w
alone.
So what disks can't be read by a pc (does the uP matter?) equipped with
1? Just curious of a few examples, not expecting a comprehensive list.
If there are any.
I haven't encountered any magnetic disks for which a flux-transition
device shouldn't be able to do it. But, there well might be. (such as
recpording audio tones, instead of flux transitioning bits)
The microprocessor does not matter, but the disk controller does.
Using just the Operating System, with no additional software, you are
limited to those disks.
We estimate that there are about 2500 different disk formats.
But, many other computers used similar disk controllers, most made by
Western Digital and NEC. With a similar controller and appropriate drive,
software in the PC can read a lot of other formats.
http://www.xenosoft.com/fmts.html
is a list of the formats that I had managed to do on PC by Y2K.
Macintosh 1.4M can be read with PC.
But, AppleII (Apple-DOS, Apple CP/M, Apple Pascal/P-System, ProDos), and
Macintosh 400K and 800K can't be easily read by PC. (GCR)
There are quite a few others with incompatabilities with the PC FDC.
Not all PC FDC's can handle FM/single-density, etc.
That is where a flux-transition device is the way to go.
There are some bizarre tricks, such as switching drives in mid-sector,
that can sometimes fool the FDC, and enable some things such as Amiga.
"Apple Turnover" was a bespoke single purpose flux-like device
specifically for handling AppleII on PC
--
Grumpy Ol' Fred cisin(a)xenosoft.com