On 6/6/21 5:21 AM, Robert G8RPI via groups.io wrote:
Err, no on else seen this:
Also this document states the 4145A disk format is "unique"
Yeah that's the guy who says it's "IBM 3740 format", and the lists 40
tracks, 9 sectors per track, and 256 bytes per sector.
IBM 3740 format is 8", not 5.25". And it's 77 tracks, 26 sectors per
track, and 128 bytes per sector. I don't know what the guy was smoking.
I think that is a little harsh Dave,
The only time he mentions 3470 is for the physcal drive, this appears to
refer to the FM recording and probably came from the MB8866 FDC data
sheet. Can't blame them for using what the FDC controller manufacturer
says it is...
I have the MB8876 datasheet from 1986 and it also refers to FM as
IBM3470 format
That aside the owner for the site seems to have correctly identified?
the disk type, format and recording method.
I'm sorry that you think I was harsh; I did not mean to offend. But
the guy is simply wrong. Yes, it's true that the IBM 3740 format uses
FM, but so do dozens, if not hundreds of other floppy disk formats.
That does not make them IBM 3740 format. It doesn't even make them
anything remotely like IBM 3740 format. The fact that one can use an
MB8876 floppy disk controller chip to make a disk subsystem that
implements the IBM 3740 format is irrelevant.
What I have a problem with here is that the guy just plopped that
specification into the web page, obviously without understanding what it
means, potentially misleading people who don't know any better if they
were to see it.
I acknowledge that he presented a bunch of otherwise-useful, and
seemingly plausible information. But given the above egregious error,
I'd feel compelled to check every bit of it before using it, which seems
a shame. IMO, a better approach would have been to just not put stuff
on such a page unless he's certain it's correct, rather than just
parroting material from a datasheet and taking specifications out of
context.
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
Dave McGuire