Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!sun-barr!newstop!texsun!pollux!attctc!wnp
From: wnp@attctc.DALLAS.TX.US (Wolf Paul)
Newsgroups: comp.sys.ibm.pc
Subject: Re: make your own HD 3 1/2 in floppies
Message-ID: <8618@attctc.DALLAS.TX.US>
Date: 11 Jul 89 21:25:50 GMT
References: <26260@amdcad.AMD.COM> <26262@amdcad.AMD.COM>
Reply-To: wnp@attctc.Dallas.TX.US (Wolf Paul)
Organization: The Unix(R) Connection BBS, Dallas, Tx
Lines: 41

In article <26262@amdcad.AMD.COM> ching@pepsi.AMD.COM (Mike Ching) writes:
>Anyone know how the 1.44Mb floppies achieve the density? More tracks?
>More sectors/track? *Should* this work? You can't use 360K 5 1/4"
>floppies at 1.2M because the coercivity of the coating is different but
>you can make them 720K by doubling the number of tracks.
>
>So how do 1.44M floppies differ from 720K ones besides the hole?

I don't know the difference in magnetic property of the medium, but as
far as formatting under DOS and other PC operating systems (UNIX, XENIX) is
concerned, 1.44M floppies are formatted with 80 tracks of 18 sectors each.

In fact, to be complete, here is a list of track/sector configurations for
most common PC disk formats:

Capacity  Tracks  Sec/Track

  320K      40      8
  360K      40      9
  400K      40     10         Notes 1, 2
  720K      80      9         Note 3
  800K      80     10         Note 2
  1.2M      80     15  
  1.44M     80     18 

Notes:

  1. This is the AT&T UNIX PC native format;

  2. There are a couple pd format programs which format double-density
     diskettes to 400K (XT-style drives) or 800K (AT-style or older
     96TPI drives), also 3.5" 720k drives);

  3. Both 5.25" and 3.5" drives use the same format;

Hope this information is helpful.
-- 
Wolf N. Paul * 3387 Sam Rayburn Run * Carrollton TX 75007 * (214) 306-9101
UUCP:   {texbell, attctc, dalsqnt}!dcs!wnp
DOMAIN: wnp@attctc.dallas.tx.us or wnp%dcs@texbell.swbt.com
        NOTICE: As of July 3, 1989, "killer" has become "attctc".