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: <8663@attctc.DALLAS.TX.US>
Date: 15 Jul 89 17:59:58 GMT
References: <26260@amdcad.AMD.COM> <26262@amdcad.AMD.COM> <14333@dartvax.Dartmouth.EDU> <563@amms4.UUCP>
Sender: 0000-Admin(0000)
Reply-To: wnp@attctc.Dallas.TX.US (Wolf Paul)
Organization: The Unix(R) Connection BBS, Dallas, Tx
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In article <563@amms4.UUCP> hjg@amms4.UUCP (Harry Gross) writes:

	(regarding the difference between 720K and 1.44M 3.5" disks)

>I posted something on this a few minutes ago.  As far as I have been able to
>determine, the only difference between the two diskettes it the use of the
>flip side for data storage.  In all probability, the second side is perfectly
>fine to use.  HOWEVER, there are no guarantees that the coating is 'computer
>grade' on the flip side of a 720K disk.  Most of the time, though, it works.

I am afraid your information is wrong. Both 720K and 1.44M 3.5" diskettes
used on PCs and 800K diskettes used on MACs are DOUBLESIDED disks. The only
SINGLESIDED 3.5" format I am aware of is the older MAC 400K format (prior to
the MAC Plus).

The difference between 720K and 1.44M disks is not the number of sides used,
but the number of 512-byte sectors written per track. 720K disks have 9
sectors per track, while 1.44M disks have 18 sectors per track.

The question with regard to the 3.5" disk notchers is, what is responsible
for the higher data density: just the design of the drives, or is the
magnetic coating of the 1.4M disks different? All I have seen and heard
on that subject so far are "guesses" -- nobody with facts.

-- 
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".