[net.micro.pc] device driver question

ctk@ecsvax.UUCP (05/03/84)

I have a question about ram disk programs that come with memory cards
and their relation to device drivers. If you use, for example, the AST
Superdrive program, the directions tell you to set the switches for one
more floppy drive than you really have. I you have a driver for nonstandard
floppies (like 80 track drives, or 3") you set the switches for fewer drives
than you really have. Is there a way out of this dilemma?
    C.T. Kelley
    Dept. of Math.
    N.C. State U.
    Raleigh, N.C. 27650
    decvax!mcnc!ecsvax!ctk

glenm@mako.UUCP (Glen McCluskey) (11/29/84)

A friend of mine has been working on developing a system
that will allow a PC to treat a file on a VAX (running VMS)
as a disk drive.  This is accomplished by writing a server
for the VAX and a device driver for the PC that knows how
to talk to the VAX server through the serial port.  There is
also a utility program that runs on the PC that can be used
to tell the VAX to create, delete, or select files to use
as virtual disks.

The problem is this:  it would be nice if the file on the VAX
did not have to be a hardwired size -- it is desirable to let
it be X number of blocks, where X is completely up to the
user.  MSDOS, however, will not recognize the size specified
in the boot block -- it gets loaded into memory whenever MSDOS
calls the driver with the BUILD_BPB instruction, but the new
size is ignored in subsequent DIR and CHKDSK commands.  MSDOS
is obviously capable of changing dynamically -- one can put a
SSSD disk into a drive and MSDOS will recognize it and won't
keep thinking there is a DSDD disk there -- but how can a
device driver force the new size to be recognized?

			Glen McCluskey
			..tektronix!mako!glenm