Path: utzoo!mnetor!uunet!steinmetz!davidsen
From: davidsen@steinmetz.steinmetz.UUCP (William E. Davidsen Jr)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Copy diskettes without formatting
Message-ID: <9784@steinmetz.steinmetz.UUCP>
Date: 4 Mar 88 14:37:01 GMT
References: <109@castor.kulcs.uucp>
Reply-To: davidsen@crdos1.UUCP (bill davidsen)
Organization: General Electric CRD, Schenectady, NY
Lines: 28
Keywords: PC-Tools copy format diskette


  Formatting is done at the track level.  That is, the actual hardware
chip must be given the format command for each track, although the BIOS
often does this for you, and the format program calls the BIOS. 

  Good format and copy routines can do the following:
	issue the format command for the track
	issue a "write multiple" command on the same track
	step to the next track

  The write operation can come soon enough after the format command to
be done on the next revolution of the disk. Since the chip is doing the
write of multiple sectors, it can write the sectors in order (1:1
interleave) and therefore the effective write speed is two tracks/sec,
based on 6 rps, one rev for format, one for write, one for step. A
verify step can be added if desirable, reducing the effective speed to
1.5 track/sec.

  There is no reason to think that a disk formatted in this way is less
reliable than any other.

CAVEAT: this is not complete. The are other details having to do with
64k boundaries, format parameters, DMA setup, etc. See the technical
manual for details.
-- 
	bill davidsen		(wedu@ge-crd.arpa)
  {uunet | philabs | seismo}!steinmetz!crdos1!davidsen
"Stupidity, like virtue, is its own reward" -me