Fred wrote:
I could be misremembering (as usual?), but
ISTR it being around DOS 3.31 that they switched from using 64K for a
buffer during DISKCOPY over to using all of RAM.
Could well be. Certainly IBM DOS 1.0 and 1.1 didn't do it. The first
program I wrote in assembly language for the PC, back in August 1981, was
a disk copy utility for IBM DOS that used all available RAM. I just wanted
it for my own use, but my employer was happy to have it for software
production. At one point I was asked to add a way to produce copy-protected
disks, but I didn't want anything to do with that.
Originally I only supported 160K disks, since that's all DOS 1.0
supported. I think someone else at the company updated it for 180K, then
320K and 360K. AFAIK the company went under before the IBM AT appeared
with its 1.2M high-density floppies.
Eric