The MASM Forum Archive 2004 to 2012

Miscellaneous Forums => 16 bit DOS Programming => Topic started by: dncprogrammer on January 22, 2007, 08:25:43 PM

Title: Diskette write order?
Post by: dncprogrammer on January 22, 2007, 08:25:43 PM
When DOS writes to disk does it switch heads after each sector or does it write one whole side of the media then return to track 0 and start on side 1?

jon
Title: Re: Diskette write order?
Post by: sinsi on January 22, 2007, 10:56:47 PM
IIRC the order for a 1.44 floppy is
  track 0, head 0, sector 1-18
  track 0, head 1, sector 1-18
  track 1, head 0, sector 1-18
  track 1, head 1, sector 1-18
  ...
  track 79, head 0, sector 1-18
  track 79, head 1, sector 1-18
Title: Re: Diskette write order?
Post by: MichaelW on January 23, 2007, 06:40:59 PM
Yes. And this access order is determined by the data layout, which was selected to maximize data transfer rates within the limits of the hardware design. A track change is much slower than a head switch because it involves physically moving the head assembly.