Commodore DOS

CBM DOSdisk operationsCBM DOS 2.5/2.7CBM DOS 2.6CBM DOS 2.7CBM DOS 3.0CBM DOS v3.0CBM-DOSDOS
Commodore DOS, also known as CBM DOS, is the disk operating system used with Commodore's 8-bit computers.wikipedia
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DOS

COM1AUX:LPT1
Unlike most other DOSes, which are loaded from disk into the computer's own RAM and executed there, CBM DOS is executed internally in the drive: the DOS resides in ROM chips inside the drive, and is run there by one or more dedicated MOS 6502 family CPUs.
Others include Apple DOS, Apple ProDOS, Atari DOS, Commodore DOS, TRSDOS, and AmigaDOS.

Disk operating system

DOSDisk Operation SystemIBM PC (DOS)
Commodore DOS, also known as CBM DOS, is the disk operating system used with Commodore's 8-bit computers.
Most home and personal computers of the late 1970s and 1980s used a disk operating system, most often with "DOS" in the name and simply referred to as "DOS" within their respective communities: CBM DOS for Commodore 8-bit systems, Atari DOS for the Atari 8-bit family, TRS-DOS for the TRS-80, and Apple DOS for the Apple II, and MS-DOS for IBM PC compatibles.

Commodore 1541

15411541 disk drive1541 floppy disk drive
Version 2.6 was by far the most commonly used and known DOS version, due to its use in the 1541 as part of C64 systems.
The drive's built-in disk operating system is CBM DOS 2.6.

Commodore bus

CBM-488serial busCBM (IEC) serial
Drives whose model number starts with 15 connect via Commodore's unique CBM-488 serial (TALK/LISTEN) protocols, all others use the parallel IEEE-488.

DOS Wedge

The DOS Wedge and various third-party cartridges and extenders such as Epyx FastLoad, Action Replay, and The Final Cartridge III allow viewing of the disk directory using special commands that load the directory into screen memory without destroying the current BASIC program.
The Wedge made disk operations in BASIC 2.0 significantly easier by introducing several keyword shortcuts.

Block availability map

BAM
When the drive is commanded to close a file that has been opened for writing, the associated buffer is flushed to the disk and the block availability map (BAM) is updated to accurately reflect which blocks have been used.
In terms of Commodore DOS (CBM DOS) compatible disk drives, the BAM was a data structure stored in a reserved area of the disk (its size and location varied based on the physical characteristics of the disk).

Commodore 1540

1540VIC-1540disk drives
The 1540 is an "intelligent peripheral" in that it has its own MOS Technology 6502 CPU (just like its VIC-20 host) and the resident Commodore DOS on board in ROM – contrary to almost all other home computer systems of the time, where the DOS was loaded from a boot floppy and was executed on the computer's CPU.

Commodore 1581

1581
The version of Commodore DOS built into the 1581 added support for partitions, which could also function as fixed-allocation subdirectories.

Commodore 1571

15711572Commodore 157x
The revised firmware for the 1571 which fixed the relative file bug was also identified as V3.0.

The Final Cartridge III

Final Cartridge
The DOS Wedge and various third-party cartridges and extenders such as Epyx FastLoad, Action Replay, and The Final Cartridge III allow viewing of the disk directory using special commands that load the directory into screen memory without destroying the current BASIC program. One popular trick, used, for example, by The Final Cartridge III, was to add files named of type to the directory, and files could then be rearranged around those lines to form groups.
The cartridge provided an extension to the Commodore BASIC, which contained several new BASIC programming aids, such as RENUMBER, and several utility commands, one of the most notable of which was DOS" which can be used to give Commodore DOS commands (e.g. DOS"S0:UNDESIRED FILE to delete a file), read the error status of the drive (plain DOS") or display the disk directory without overwriting the BASIC program in the memory (DOS"$).

Commodore BASIC

BASIC 2.0BASIC 7.0BASIC
File names may contain a shifted space character, and if the directory listing is being viewed from BASIC, the portion of the file name beyond the character will appear to have been separated from the first part of the file name by a quotation mark, causing BASIC to not consider it to be part of the full file name.

Block allocation map

BAM
The Commodore DOS used a similarly named but significantly different Block availability map.

Commodore International

CommodoreCommodore Business MachinesCommodore 64
Commodore DOS, also known as CBM DOS, is the disk operating system used with Commodore's 8-bit computers.

Random-access memory

RAMmemoryrandom access memory
Unlike most other DOSes, which are loaded from disk into the computer's own RAM and executed there, CBM DOS is executed internally in the drive: the DOS resides in ROM chips inside the drive, and is run there by one or more dedicated MOS 6502 family CPUs.

Read-only memory

ROMRead Only MemoryROMs
Unlike most other DOSes, which are loaded from disk into the computer's own RAM and executed there, CBM DOS is executed internally in the drive: the DOS resides in ROM chips inside the drive, and is run there by one or more dedicated MOS 6502 family CPUs.

MOS Technology 6502

6502MOS 6502M6502
Unlike most other DOSes, which are loaded from disk into the computer's own RAM and executed there, CBM DOS is executed internally in the drive: the DOS resides in ROM chips inside the drive, and is run there by one or more dedicated MOS 6502 family CPUs.

Central processing unit

CPUprocessorprocessors
Unlike most other DOSes, which are loaded from disk into the computer's own RAM and executed there, CBM DOS is executed internally in the drive: the DOS resides in ROM chips inside the drive, and is run there by one or more dedicated MOS 6502 family CPUs.

Local area network

LANlocal networklocal
Thus, data transfer between Commodore 8-bit computers and their disk drives more closely resembles a local area network connection than typical disk/host transfers.

Commodore 64

C6464Commodore
Version 2.6 was by far the most commonly used and known DOS version, due to its use in the 1541 as part of C64 systems.