On 5/27/21 12:21 PM, Fred Cisin via cctalk wrote: > In 1981, when the Osborne 1 came out, I got some sample disks from it. > So, other than TRS80s, which I had, those were also the first samples > that I worked with. I manually, a sector at a time, copied some files > from those Osborne 1 disks using Superzap on TRS80. THAT was the > preliminary success that convinced me that it could be done, and gave > the the impetus and confidence to write XenoCopy, in the next few years, > after the 5150 came out. (5150 came out August 11, 1981, but it took me > 5 months to get one) BUT, the 5150 couldn't do FM Single Density, so > the PC-DOS version of XenoCopy didn't get an Osborne format until the > MFM Double Density upgrade for the Osborne 1 came out.
I'd been cutting floppy controller code since about 1975; the weirdness of the IBM PC design really made for some head-scratching. Sometime in the 5150/5160 days, I published instructions on how to modify a PC floppy controller that used the 765 with a WD926 data separator. It was quite simple--for some unknown reason, both of the clock rate select lines were hard-wired. Getting FM support was mostly a matter of lifting one of those lines and running a jumper to the MFM/FM output on the 765. But then IBM and clones did the same sort of thing with the parallel port adapter. Changing one to bidirectional (and curiously PS/2-compatible) was mostly a matter of lifting the output enable line on an IC and tying it an unused bit in the control port. Sometimes I wonder if IBM did this sort of stuff intentionally. --Chuck
