CBMFS - Revision history

John e at 09:38, 21 November 2024

2024-11-21T09:38:22Z

Jsummers at 22:05, 4 June 2017

2017-06-04T22:05:50Z

VolodyA! V Anarhist: /* CBM DOS Directory Structure */ wikify another table

2015-06-09T06:35:10Z

‎CBM DOS Directory Structure: wikify another table

VolodyA! V Anarhist: /* Variations on the D64 layout */ more wikifications of tables

2015-06-09T06:29:34Z

‎Variations on the D64 layout: more wikifications of tables

Show changes

VolodyA! V Anarhist: /* Physical media */ wikification of tables

2015-06-09T06:01:36Z

‎Physical media: wikification of tables

Dan Tobias at 02:18, 22 April 2014

2014-04-22T02:18:53Z

Dan Tobias at 17:53, 5 October 2013

2013-10-05T17:53:06Z

Dan Tobias at 00:07, 23 May 2013

2013-05-23T00:07:31Z

Dan Tobias at 12:54, 22 May 2013

2013-05-22T12:54:56Z

Dan Tobias at 12:52, 22 May 2013

2013-05-22T12:52:00Z

← Older revision		Revision as of 09:38, 21 November 2024
Line 622:		Line 622:

	(Content taken from [http://unusedino.de/ec64/technical/formats/d64.html D64.TXT] in Peter Scheper's excellent compendium of C64 file format information).		(Content taken from [http://unusedino.de/ec64/technical/formats/d64.html D64.TXT] in Peter Scheper's excellent compendium of C64 file format information).
		+
		+	== Commodore C64 CP/M Filesystem ==
		+
		+	A D64 file written by the Commodore 64 port of [[CP/M]] will contain a [[CP/M file system]]. This has the following characteristics:
		+	* 34 tracks
		+	* 2 system tracks
		+	* 17 256-byte sectors per track (appearing to CP/M as 34 128-byte sectors)
		+	* 1k blocks
		+	* 2 directory blocks
		+
		+	The CP/M filesystem is found on the first 17 sectors of each track (except track 18, which is skipped). CP/M numbers tracks from zero, so tracks 1-17 are accessed as 0-16, and tracks 19-35 as 17-33.
		+
		+	The CBMFS block availability map marks all sectors as used. The disk name is usually "CP/M DISK".
		+
		+	On a boot disk, the first sector contains a BASIC bootloader (present in the CBMFS directory as the file "CPM"). The remaining sectors of tracks 1 and 2 contain the 6502 host code and the CP/M BIOS, BDOS and CCP.

	== Utilities ==		== Utilities ==

@@ Line 463: / Line 463: @@
 | Seek
 | Checksum error in header block
-| The  header  block  contains  a   checksum   value, calculated by XOR'ing the TRACK,  SECTOR,  ID1  and ID2 values. If this checksum is wrong,  this  error is generated.
+| The  header  block  contains  a   checksum   value, calculated by [[Exclusive Or|XOR'ing]] the TRACK,  SECTOR,  ID1  and ID2 values. If this checksum is wrong,  this  error is generated.
 |-
 | 0B

@@ Line 272: / Line 272: @@
 from bytes $02-$34.
-      2       3       4       5       6
+{| class='wikitable'
-  ----    -----   -----   -----   -----   -----
+! 1
-/0    17/10   17/20   17/1    17/11    0/52
+! 2
- (11/00) (11/0A) (11/14) (11/01) (11/0B)  (0/34)
+! 3
 == Variations on the D64 layout ==

@@ Line 16: / Line 16: @@
 The original media (a 5.25" disk) has the tracks  laid  out  in  circles, with track 1 on the very outside of the disk  (closest  to  the  sides)  to track 35 being on the inside of the disk (closest to the inner  hub  ring). Commodore, in their infinite wisdom, varied the number of sectors per track and data densities across the disk to optimize available storage, resulting in the chart below. It shows the sectors/track for a  standard  D64.  Since the outside diameter of a circle is  the  largest  (versus  closer  to  the center), the outside tracks have the largest amount of storage.
-        Track   Sectors/track   # Sectors   Storage in Bytes
+{| class='wikitable'
-        -----   -------------   ---------   ----------------
+! Track
--17        21            357           7820
+! Sectors/track
--24        19            133           7170
+! # Sectors
--30        18            108           6300
+! Storage in Bytes
--40(*)     17             85           6020
+|-
-                                   ---
+| 1-17
-(for a 35 track image)
+| 21
-  Track #Sect #SectorsIn D64 Offset   Track #Sect #SectorsIn D64 Offset
+Sectors (for a 35 track image)
-  ----- ----- ---------- ----------   ----- ----- ---------- ----------
-     21       0       $00000      21     19     414       $19E00
-     21      21       $01500      22     19     433       $1B100
-     21      42       $02A00      23     19     452       $1C400
-     21      63       $03F00      24     19     471       $1D700
-     21      84       $05400      25     18     490       $1EA00
-     21     105       $06900      26     18     508       $1FC00
-     21     126       $07E00      27     18     526       $20E00
-     21     147       $09300      28     18     544       $22000
-     21     168       $0A800      29     18     562       $23200
-     21     189       $0BD00      30     18     580       $24400
-     21     210       $0D200      31     17     598       $25600
-     21     231       $0E700      32     17     615       $26700
-     21     252       $0FC00      33     17     632       $27800
-     21     273       $11100      34     17     649       $28900
-     21     294       $12600      35     17     666       $29A00
-     21     315       $13B00      36(*)  17     683       $2AB00
-     21     336       $15000      37(*)  17     700       $2BC00
-     19     357       $16500      38(*)  17     717       $2CD00
-     19     376       $17800      39(*)  17     734       $2DE00
-     19     395       $18B00      40(*)  17     751       $2EF00
-   (*)Tracks 36-40 apply to 40-track images only
+{| class='wikitable'
 ==CBM DOS Directory Structure ==

@@ Line 5: / Line 5: @@
 The '''CBM File System''' was used by disk drives made by Commodore Business Machines for the  PET, VIC-20, C64 and C128 range of computers. These drives were called 'intelligent peripherals' meaning the DOS (Disk Operating System) was run in the drive itself, not on the computer the drive was attached to.
-The most popular CBM drive was the [[Commodore 1541 disk|1541]], which supported 35 tracks using [[GCR encoding]].  A later drive, the [[Commodore 1571 disk|1571]] disk, used a double-sided format for twice the space. 3 1/2" disks were later introduced to the Commodore via the [[Commodore 1581 disk|1581]] format.
+The most popular CBM drive was the [[Commodore 1541 disk|1541]], which supported 35 tracks using [[GCR encoding]].  A later drive, the [[Commodore 1571 disk|1571]] disk, used a double-sided format for twice the space. 3 1/2" disks were later introduced to the Commodore via the [[Commodore 1581 disk|1581]] format, which used a variant of CBMFS (see [[Commodore 1581 filesystem]]).
 == D64 File Format ==

← Older revision		Revision as of 17:53, 5 October 2013
Line 529:		Line 529:
	(Content taken from [http://unusedino.de/ec64/technical/formats/d64.html D64.TXT] in Peter Scheper's excellent compendium of C64 file format information).		(Content taken from [http://unusedino.de/ec64/technical/formats/d64.html D64.TXT] in Peter Scheper's excellent compendium of C64 file format information).

		+	== Utilities ==
		+	* [http://style64.org/dirmaster DirMaster: reads C64 disk images / archives / files in Windows]

	[[Category:Commodore computers]]		[[Category:Commodore computers]]

@@ Line 3: / Line 3: @@
 |subcat=Filesystem
 }}
-The CBM File System was used by disk drives made by Commodore Business Machines for the  PET, VIC-20, C64 and C128 range of computers. These drives were called 'intelligent peripherals' meaning the DOS (Disk Operating System) was run in the drive itself, not on the computer the drive was attached to.
+The '''CBM File System''' was used by disk drives made by Commodore Business Machines for the  PET, VIC-20, C64 and C128 range of computers. These drives were called 'intelligent peripherals' meaning the DOS (Disk Operating System) was run in the drive itself, not on the computer the drive was attached to.
 The most popular CBM drive was the [[Commodore 1541 disk|1541]], which supported 35 tracks using [[GCR encoding]].  A later drive, the [[Commodore 1571 disk|1571]] disk, used a double-sided format for twice the space. 3 1/2" disks were later introduced to the Commodore via the [[Commodore 1581 disk|1581]] format.

@@ Line 7: / Line 7: @@
 The most popular CBM drive was the [[Commodore 1541 disk|1541]], which supported 35 tracks using [[GCR encoding]].  A later drive, the [[Commodore 1571 disk|1571]] disk, used a double-sided format for twice the space. 3 1/2" disks were later introduced to the Commodore via the [[Commodore 1581 disk|1581]] format.
-==D64 File Format ==
+== D64 File Format ==
 The [[D64]] format is most frequently used to capture 1541 disk images, it consists of a sector-for-sector copy of a 1540/1541 disk.  The standard D64 is a 174848 byte file comprised of 256 byte sectors arranged in 35 tracks with a varying number of  sectors  per  track for a total of 683 sectors. Track counting starts at 1, not 0, and goes  up
 to 35. Sector counting starts at 0, not 1, for the first sector,  therefore a track with 21 sectors will go from 0 to 20.
 The original media (a 5.25" disk) has the tracks  laid  out  in  circles, with track 1 on the very outside of the disk  (closest  to  the  sides)  to track 35 being on the inside of the disk (closest to the inner  hub  ring). Commodore, in their infinite wisdom, varied the number of sectors per track and data densities across the disk to optimize available storage, resulting in the chart below. It shows the sectors/track for a  standard  D64.  Since the outside diameter of a circle is  the  largest  (versus  closer  to  the center), the outside tracks have the largest amount of storage.