On 06/02/2016 05:09 PM, Fred Cisin wrote: > I hope that Chuck will correct some of the errors that I made below:
I think you've pretty much got it. > No need for drivers IFF your hardware (FDC and BIOS) and OS were new > enough. I think that SOME FDC boards that supported 2.8M data > transfer rates had BIOS chip to "update" the system BIOS. If the 2.88M-capable FDC wasn't part of the motherboard, it generally had a BIOS on the card for the extra stuff. This was certainly true of the CompatiCard IV and a few other "special" FDCs (i.e., those with a separate connector for a 2.88M drive). NT 4 had no problem with the drives, but then, it could also support 3-mode drives (1.23M 360RPM 8x1024 format). I believe that pin 4 on the floppy interface was used to switch speeds. > Was it 4.00 that added 2.8M? Sounds right--but it may also be a matter of *which* 4.0. MS or IBM? > DRIVER.SYS V DRIVPARM=: DRIVER.SYS permitted using formats that were > newer than the SETUP program knew about, such as 720K 3.5" on 5150 > and 5160, or pre 3.5" 5170. DRIVER.SYS created an additional drive > letter, so the 3.5" drive would end up as drive D: > > DRIVPARM changed the specs of the drive without creating a new > letter, so your 3.5" could still be B: DRIVPARM was undocumented in > PC-DOS 3.20 and 3.30, but it WAS there, and worked just fine with > generic BIOS. BUT, I was surprised to find it FAILING with real IBM > BIOS (or image thereof) in the same machine! Good reason to leave > it out of the manual! DRIVPARM was sort-of-disabled on PC-DOS 3.2 and 3.3. You had to suffix the "DRIVPARM" with three control-A characters (hex 01) to get it to work. At some point, the device types for SD and DD 8" drives were nulled out, but I don't recall when. > BTW, if you had four floppies installed, and the BIOS understood, > then your floppies would be drives A:. B:, C:, and D:. and you hard > drive would be drive E:. But some programs were "hard-wired" to > assume C: as the hard drive, including the INSTALL for MS-DOS 5.00! > MICROS~1's answer: "Install it on drive C:, and then copy it to the > hard drive that you want it on." I refused to install it to a 3" > disk, so I installed on a different machine, and created a 360K boot > disk, plus copied all of the other files to a sub-directory on the > hard disk (E:). At some point, MSDOS decided that the hard disk would always be C:, with any additional removable drives trailing that. That probably helped a lot. And there was always a drive B:, whether or not a physical drive was present (if not, it mapped to drive A: with suitable prompting messages). --Chuck
