[comp.sys.ibm.pc] Diff between 720K, 1.2M floppies?

edw@ihuxm.ATT.COM (Ed Windes) (04/30/87)

I have a Teac FD-55FV-13-U,  5-1/4", 96tpi floppy drive.
I am using it in a PC clone as a 720K drive.

What is the difference between this drive and an 1.2M AT drive?
The pidgin English document included with my drive covers the
55BV drive (360K) and the 55GFV drive (1.2M) - but doesn't mention
my drive.  Can I select between the two formats with a jumper?

Does anyone have a number for Teac customer service?  The document
notes:
	"...in actual application, further discussion of
	users might be required.  We would appreciate
	receiving your advise and comments on this application
	notes.  Please inform to the nearest TEAC office."
	
-- ed windes,  ihnp4!ihopa!edw, (312)979-5748
  -- at&t bell labs, naperville, il 6056 so hogr

farren@hoptoad.UUCP (05/01/87)

In article <1597@ihuxm.ATT.COM> edw@ihuxm.ATT.COM (Ed Windes) writes:
>I have a Teac FD-55FV-13-U,  5-1/4", 96tpi floppy drive.
>I am using it in a PC clone as a 720K drive.
>
>What is the difference between this drive and an 1.2M AT drive?
>The pidgin English document included with my drive covers the
>55BV drive (360K) and the 55GFV drive (1.2M) - but doesn't mention
>my drive.  Can I select between the two formats with a jumper?
>

The 55GFV is a 96 tpi drive, but uses special heads and media to
achieve the 1.2M capacity.  I think they also rotate at a different
speed for 1.2M, but am not sure.  You cannot select between the two
formats on the 55FV, although a 55GV can read 720K formats as well as
1.2M.  In general, higher capacity drives can read lower capacity
formats, and not vice versa.
-- 
----------------
                 "... if the church put in half the time on covetousness
Mike Farren      that it does on lust, this would be a better world ..."
hoptoad!farren       Garrison Keillor, "Lake Wobegon Days"

davidsen@steinmetz.steinmetz.UUCP (William E. Davidsen Jr) (05/01/87)

In article <1597@ihuxm.ATT.COM> edw@ihuxm.ATT.COM (Ed Windes) writes:
>I have a Teac FD-55FV-13-U,  5-1/4", 96tpi floppy drive.
>I am using it in a PC clone as a 720K drive.
>
>What is the difference between this drive and an 1.2M AT drive?
>The pidgin English document included with my drive covers the
>...

To use a 96 tpi drive for 1200k you need three things: the right
controller, the right software, and the special speed drive.

The 1200k drives turn at 360 rpm rather than 300, and have a
transfer rate of 500k rather than 250. If this sounds just like
an 8" disk drive, it is. I'm told that a standard AT controller
will run an 8" drive with a little diddling of cables. I suspect
that you are lacking some (or all) of the requirements. People
with 1200k drive can run 720k on cheap floppies, however, which
is a much lower cost per byte than the 1200k.

-- 
bill davidsen			sixhub \	ARPA: wedu@ge-crd.arpa
      ihnp4!seismo!rochester!steinmetz ->  crdos1!davidsen
				chinet /
"Stupidity, like virtue, is its own reward"