[Coco] DECB FAT question

[Willard Goosey]

>Date: Wed, 17 Jan 2007 14:02:48 -0600
>From: Roger Taylor <operator at coco3.com>

>Almost all Disk BASIC floppy disks have lots of "free space" on them 
>even when the disks report as being FULL.  How so?  The reason is 
>that the File Allocation system reserves 9 sectors at a time, no 
>matter if the files need them or not.

It is a rather large cluster size, but on an 18 sector / track disk,
the only other sizes that come out even 1 or 2 sectors/granule.  And
those would require 16-bit granule numbers, even on a single-sided 35
track disk. (630 or 315 granules / disk.  OK, 10 or 9 bits.  While
Microsoft is the home of the 12-bit FAT, they had to fit everything in
an 8K ROM.)

Trust me, having clusters (granules, groups, whatever) that don't fit
an even number of times into a track make for a lot more housekeeping.
Disk BASIC is easy enough to confuse as it is...

Willard
-- 
Willard Goosey  goosey at sdc.org
Socorro, New Mexico, USA
"I've never been to Contempt!  Isn't that somewhere in New Mexico?"
   --- Yacko