Source for a fat move...

 BBS: Inland Empire Archive
Date: 02-12-93 (02:12)             Number: 374
From: DIK COATES                   Refer#: NONE
  To: CHRIS TRACY                   Recvd: NO  
Subj: Source for a fat move...       Conf: (2) Quik_Bas

>>>> QUOTING Chris Tracy to All <<<<

 CT> Does anyone have the source for like a FAT move? The ones

Like a copy to another file, or printer?  Shouldn't be too
difficult... the FAT starts at sector 1 (Reserved area preceeds
it, starting at logical sector 0) and the size is:

  disk size                 FAT size   Root Dir Size

for .36M disks             4 sectors       7 sectors
for 1.2M disks            14 sectors      14 sectors
for .72M disks             6 sectors       7 sectors
for 1.44M disks           18 sectors      14 sectors
Hard Disks          varies see below      32 sectors

The number of sectors per FAT for fixed disks is contained in the
boot sector (0).  Sector 0 is the first sector on the drive or
partition.  The following info on sector 0:

offset     length   comment

  00h     3 bytes   jump to start location
  03h     8 bytes   System ID
  0Bh     2 bytes   Bytes/sector
  0Dh     1 byte    sectors/cluster
**0Eh     2 bytes   sectors in reserved area
  10h     1 byte    number of FAT copies
  11h     2 bytes   number of root directory entries
  13h     2 bytes   total number of sectors
  15h     1 byte    media descriptor
**16h     2 bytes   number of sectors per FAT
  18h     2 bytes   sectors/track
  1Ah     2 bytes   number of heads
  1Ch     2 bytes   number of hidden sectors

All disks/diskettes have the following form:

Sector
  0       Reserved Area (see above)... diskettes 1 sector long
 **       FAT (see above)
 **       Root Directory
 **       Files Area

Use Int calls to determine media types, and read directly from
sectors for info... If writing to the reserved or FAT area...
take 'er easy... can do a bucket of grief, without trying too
hard... A backup helps, even after you reformat!

Hope I've confused you... Dik, Oshawa, Canada

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