I have a bunch of .dsk RT11 400k image files I need to write toRX50 disks so I can boot from them on my 11/73such as: PBM 1000 Tandy 2000. . . IBM PC/JX
On Thu, 14 Sep 2017, Warner Losh wrote:
Right. I didn't see the Atari on the list, which was the only one, prior to this thread, that I knew for sure had the right drives in it... I also misread the IBM PC/JX as pcjr, which had the 360k floppy drive in it.
Yes, the PC/JX was kinda obscure. (Japan?, Australia?) It was never sold in USA. There were quite a few more. I have difficulty remembering a lot of them.
On the IBM PC/AT (5170) with 1.2M, admittedly the only one that is easily readily available, there is trivial software tweaking required to format/write "720K"/"quad" density, instead of "high" density: 300 bps with single speed (360RPM) drive; 300 RPM/low density for dual speed drive. Admittedly, none of the Dec Rainbow 100 diskettes that I wrote with PC/AT are more than 30 years old. Yet.
You need hardware tweaks as well to make the drives compatible. Otherwise the recording strength is too high.
Actually, that can be done in software on virtually all such systems, certainly the OEM IBM AT. The capability is there, in order to handle 360K. The problem is getting the drive to single step (96tpi) while using the recording strength, (and rotational speed and data transfer rate) normally associated with the 360K. I have run into a few after-market clones that made that difficult.
But, the software could be a lot simpler with a 720K drive, such as Teac 55F, Shugart 465, Mitsubishi 4853, or even the old Tandon TM100-3 or TM100-4 (NOT the TM100-4M, which was 100tpi for Micropolis compatability)
There were many other brands, but I don't remember all of them.And, of course even simpler with PC (5150) or XT (5160) FDC and using 720K drive, where you didn't even have to get around FDC "features".
The problem is people try to write RX-50 media with the HD drives. The difference in recording strength causes many of the retention issues. It works better when you write with the IBM drive with HD media. This may also be drive specific, as the different drive makers have had different levels of competence with the old standards...
Yeah.If people record at the HD level on DD disks, there will be problems, and recording DD on HD disks gives an extremely short data retention! We had a buyer in the college who insisted on getting us Roytype (600 oersted?) diskettes, that would go blank minutes after writing on TRS80.
Yes. I ran TEAC FDC55FRs in my Rainbow for years to get double-sided space (with tweaks to DOS from a gentleman in New Mexico).
I used a lot of 55F (before the 55FR) drives on PCs. Also the Shugart 465.
55E was the single sided version.Anything that it could do could, of course, be done with the 55F, by leaving it on side 'A'
55B was the 360K; 55A was SS.Some of the earliest 55G (HD 96tpi) s'posedly only went to 77 tracks! Some of those could make it to track 79, but not always reliably.
TEAC 55GF was a pretty reliable drive that could work in place of either the 55F or 55G (1.2M). it worked very nicely for systems to do both 1.2M and 720K.
55FR was newer version of the 55F ('R" was "revised"?)
Circuitry "improvements"? and lower power consumption.
There were 55BR, 55FR, 55GR, and 55GFR.
The A (48tpi SS) and E (96tpi SS) were discontinued when they came out
with the R revisions.
I originally put two TM100-2 drives into my first 5150 (1981). DS support didn't come out until DOS 1.10, but there was a strange set of patches for 1.00 to use the second side as if it were another drive. When Shugart came out with their half-height drives (The Qumetrak 142 was not reliable enough), I changed it to 2 455s and 2 465s. Later I replaced one of the 465s with a 55F and when DOS 3.20 came out, replaced the other 465 with a 3.5". For a little while, I played with Vista, Maynard, and a few other controllers that supported [external] 8".
