> > Because of this a high density disk which is > > theoratically two megabytes comes up as merely 1.44 > > megabytes. There is a certain amount of material > > wasted.
> Hmmm? Isn't this because of data redundancy that prevents data loss in > case of trouble? (think stuff like parity control, checksums, etc.) It's because of sector formatting. Here's a section of track, full of 1s and 0s: -------------------------------------------------------------------- 10101010101010101010101010101010101010101010101010101010101010101010 -------------------------------------------------------------------- Here's the end of a sector and the beginning of the next: -------------------------------------------------------------------- 0101010101010XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX11101010110 -------------------------------------------------------------------- First, part of that data is the sector header, which uses up a bit of space. Second, part of that data is not data... Those "X"es are unused "potential bits". Why? because the next time you write a sector the timing may be slightly different and it may end up looking like this: -------------------------------------------------------------------- 0000000000000000101010100101010101010XXXXXXXXXXXXXXXXXXXX11101010110 -------------------------------------------------------------------- If the previous sector had started right after it, you'd have just overwritten the sector header and destroyed the sector. On the Amiga, they wrote the entire track in one pass, so you only had to put the inter-sector gap at the end of the track. That gave you 1760K on a 2Mo flippy. You could also drop most of the sector headers by modifying AmigaDOS and get 1920K in a 2Mo floppy, so long as you didn't care that you could only read it on a similarly modified AmigaDOS. -- Compact Macs is sponsored by <http://lowendmac.com/>. Support Low End Mac <http://lowendmac.com/lists/support.html> Compact Macs list info: <http://lowendmac.com/lists/compact.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:compact.macs@mail.maclaunch.com> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/compact.macs%40mail.maclaunch.com/> --------------------------------------------------------------- iPod Accessories for Less at 1-800-iPOD.COM Fast Delivery, Low Price, Good Deal www.1800ipod.com ---------------------------------------------------------------
