Just out of curiosity, is there any reason you can't either buy what you're
asking for off-the-shelf in the form of, e.g., LapLink or else use an
interface that's better suited to the problem to begin with (such as Ethernet
or even those USB "networking" cables)?

An even better solution would be to cobble the destination drive
into the source-drive's PC, do a big XCOPY, and uncobble it.
Unfortunately, in my situation the drives are NOT compatible, either.

Neither do the computers I'm working with have Ethernet or USB.

And there's almost a times-100 ratio in speed; to copy a 1 gig
disk via laplink will take about 24 HOURS vs about 17 MINUTES via
the parallel port.

Besides, there's always the fun of doing it, and that much time
difference should even "pay" for the programming effort.

--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
NRA Life Member and Rifle, Pistol, & Home Firearm Safety Certified Instructor
Certified Instructor for the Kansas Concealed-Carry Handgun license