Re: Nibble Images ...

[bidulecornu@hotmail.com (Vincent Joguin)]

Rubywand <rubywand@swbell.net> wrote in message news:<408218D6.C02C376@swbell.net>...
>      About your process for reading non-PC diskettes: Could it work for Apple
> II diskettes with one drive if a Read started with a PC diskette in the drive?
> As soon as the Disk Controller detects and starts reading the PC diskette,
> could you prompt to swap in an Apple II diskette and continue?
> 

No, that would be too easy ;-)
Unfortunately, when the controller is fired reading a sector, it can't
be stopped. If it's not serviced in time, it will return an error
(with a "not serviced in time" flag set) and will finish the read
command.

Anyway, if you've got a PC 5.25" drive, I suppose it's not a big issue
to also have a 3.5" drive in the same computer, but I agree it would
have been cooler to be able to use just one drive.

Lastly, in fact, it's partially possible to read a track (even an
Apple 2 track) with a single drive. Read the 1DISKDRV.TXT file in the
DOCS\TECH subdirectory of the archive which explains (for the Amiga,
but Apple 2 is the same in this case) how little room on a track is
necessary to be able to read the rest back. Again, unfortunately, the
Apple 2 drive (as well as most drives of the time, except on IBM
machines) doesn't take the index signal into account (well, there may
even not be an index signal at all with the disk II, but I don't know
it enough to be sure), so the "formatting technique" explained cannot
work reliably without killing one or two sectors randomly before
getting a chance to read them...

If you wanna have only 1 disk drive in the computer, the best way to
go is with the Disk2FDI cable ;-) The dumping speed to the DO format
is also very fast with it.

Vincent Joguin.