Multi-platform distribution format (Was: Backups [was
cclist at sydex.com
Sun Sep 20 20:55:30 CDT 2015
On 09/20/2015 05:32 PM, Fred Cisin wrote:
> But, I had thought that there should then be a SECOND standard for
> 5.25", for those machines without 8" support. Gary disagreed. Having
> more than ONE "standard" makes it not completely a standard. Still,
> a 5.25" "recommended" format, or a specific family with sides and
> densities, would have made a lot of people less miserable, (did we
> really need thousands of mutually incompatable formats?), and I would
> have been programming some other project.
Well, the 5.25" world was far less organized than the 8". We didn't
have an IBM to set some sort of widely-accepted standard. The 3740
format also served to cement the notion of a 128-byte sector firmly
within CP/M (and early MS-DOS) long after that sector size had ceased to
be a real physical concept.
But consider--the early Shugart (what was it, SA-400?) floppies recorded
35 tracks at 48 tpi single-sided. At a 250KHz clock, that's what, 16
sectors * 128 bytes * 35 tracks = 70KiBytes. What good is that?
At the same time Micropolis was working a 5.25" drive that could hold
about as much as an 8", using some tricks. The Micropolis drive was 100
tpi, 77 track and, by using GCR, could hold 12 512-byte sectors per
track. That's 462KiB. This was about 1977-78.
So which should have Gary embraced? The Shugart drive was dirt-simple,
but didn't hold much, but was (compratively) cheap. The Micropolis
drive and controller implementation (ours was done by a guy we'd
recruited from Sperry ISS) was more complex and expensive, but gave you
a useful amount of storage.
There weren't any really good choices for several years. Keep in mind
that 96 tpi drives also made their appearance.
The other day, I had to figure out why a fellow with CNC disks written
using a Teac FD-50C couldn't read his disks in a normal 1.2MB AT drive.
Well, the Teac beast is one of the very few 100 tpi drives that Teac
made--and this was for a system manufactured in the early 1980s.
So it was still fragmented.
And the nuttiness continued well into the 90s and the 3.5" drives (cf.
the Mac 400 and 800K GCR flooppies). I routinely get Brother WP disks
that are 38 track, single-sided, Brother-encoded GCR that hold a
whopping 120K on 2D floppies. On the other hand, they're extremely
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