3B1<->3B2

[Leslie Mikesell]

In article <10800004 at fthood> egray at fthood.UUCP writes:
>
>>='Wonder if Emmett Grey might be willing to hack a "3b2.tools" thingie
>>=for the 3b1, at some point? 
>>

>Seriously...  Somebody give me access to their 3b2 and stay on the phone
>with me while I'm testing it out, and I'll create a 3b2 version of Mtools.
>Any takers?

Mtools will work on the 3B2 as-is with the limitation that you need to prepare
a disk image that looks like a 720K DOS format with the last track locked out
or used.  This same disk can be accessed by some AT style 1.2M drives (if
the BIOS knows about 720 formats and doesn't insist on double-stepping).

The 3B2 driver does something internally with the last track and will not
access it normally (i.e "cp /dev/rSA/diskette1 /tmp/test" gives a file
that is 728064 characters long.

I tested the technique by preparing a 720 DOS formatted disk with a directory
entry for a hidden file that contained the last track (using Norton utilities).
Then I used debug to copy the 1st 18 sectors from this disk into an ordinary
file, which I transferred to the 3B2.  Then I cp'ed this dos directory image
onto a 3B2 formatted floppy producing a disk that both mtools and an
AT&T 6386 running Dos 3.2 could access.

It might be possible to modify mtools to double-step for a 360k dos disk
but it will probably require a different driver to access that last track.
As others have noted, there is a commercial program to allow this.  We
happen to have a starlan network with the DOS server software so I can
simply copy files over the network to/from PC disks, so I haven't pursued
the matter further than determining that it can be done.

Les Mikesell