Class | DOSDisk |
In: |
lib/DOSDisk.rb
|
Parent: | DSK |
Disk image with a standard Apple DOS 3.3 VTOC at track $11, sector $00
VTOC : Volume Table of Contents (from Beneath Apple DOS pp 4-2 & 4-3)
00 not used 01 track number of first catalog sector 02 sector number of first catalog sector 03 release number of DOS used to INIT this disk 04-05 not used 06 Diskette volume number (1-254) 07-26 not used 27 maximum number of track/sector pairs which will fit in one file track/sector list sector (122 for 256 byte sectors) 28-2F not used 30 last track where sectors were allocated 31 direction of track allocation (+1 or -1) 32-33 not used 34 number of tracks per diskette (normally 35) 35 number of sectors per track (13 or 16) 36-37 number of bytes per sector (LO/HI format) 38-3B bit map of free sectors in track 0 3C-3F bit map of free sectors in track 1 40-43 bit map of free sectors in track 2 ... BC-BF bit map of free sectors in track 33 CO-C3 bit map of free sectors in track 34 C4-FF bit maps for additional tracks if there are more than 35 tracks per diskette
CATALOG (from Beneath Apple DOS p 4-6)
00 Not Used 01 track number of next catalog sector 02 sector number of next catalog sector 03-0A not used 0B-2D First file descriptive entry 2E-50 Second file descriptive entry 51-73 Third file descriptive entry 74-96 Fourth file descriptive entry 97-B9 Fifth file descriptive entry BA-DC Sixth file descriptive entry DD-FF Seventh file descriptive entry
FILE DESCRIPTIVE ENTRY (from Beneath Apple DOS p 4-6)
00 Track of first track/sector list sector, if this is a deleted file this contains FF and the original track number is copied to the last byte of the file name (BYTE 20) If this byte contains a 00, the entry is assumed to never have been used and is available for use. (This means track 0 can never be used for data even if the DOS image is 'wiped' from the disk) 01 Sector of first track/sector list sector 02 File type and flags: 80+file type - file is locked 00+file type - file is not locked 00 - TEXT file 01 - INTEGER BASIC file 02 - APPLESOFT BASIC file 04 - BINARY file 08 - S type file 10 - RELOCATABLE object module file 20 - a type file 40 - b type file 03-20 File Name (30 characters) 21-22 Length of file in sectors (LO/HI format)
TRACK/SECTOR LIST FORMAT (from Beneath Apple DOS p 4-6)
00 Not used 01 Track number of next T/S list of one is needed or zero if no more t/s list 02 Sector number of next T/S list (if one is present) 03-04 Not used 05-06 Sector offset in file of the first sector described by this list 07-oB Not used 0C-0D Track and sector of first data sector or zeros 0E-0F Track and sector of second data sector or zeros 10-FF Up to 120 more track and sector pairs