QDOS 0.1 (August 1980)
first version shipped by Seattle Computer Products (QDOS = Quick and Dirty Operating System)

86-DOS 0.3 (December 1980)
first version delivered to Microsoft

86-DOS 1.0 (April 1981)
first completed release

86-DOS 1.14 (July 1981)
bought by Microsoft from Seattle Computer Products on July 27, 1981 to become MS-DOS 1.0

PC DOS 1.0 / MS-DOS 1.0 (August 1981)
developed by Seattle Computer Products and Microsoft
IBM developed COMP, DISKCOMP, DISKCOPY, MODE
distributed on 1 160KB floppy disk
initial release (equivalent to 86-DOS 1.14)
released with the IBM PC
PC DOS system files are IBMBIO.COM and IBMDOS.COM, command shell is COMMAND.COM
executable file formats are .COM and .EXE
single-sided 160KB floppy disk support (FAT12)
directory entries only include the date last written
file attributes read-only (01h), hidden (02h) and system (04h) supported
batch files (.BAT) and AUTOEXEC.BAT
internal commands: COPY, DIR, ERASE, PAUSE, REM, RENAME, TYPE
external commands: CHKDSK, COMP, DATE, DEBUG, DISKCOMP, DISKCOPY, EDLIN, FORMAT, LINK, MODE, SYS, TIME
external commands: BASIC and BASICA (PC DOS only)
special device names: AUX, COM1, CON, LPT1, NUL, PRN
program loading and execution implemented in COMMAND.COM
PSP created for each executed program
INT 22h and 23h vectors saved in PSP
files are opened with FCBs
DPB structures are used for internal drive info
INT 20h terminate program
INT 21h DOS API functions 00h-2Dh (18h, 1Ch-20h unused)
INT 22h termination address
INT 23h control break handler address
INT 24h critical error handler address
INT 25h absolute disk read (implemented in IBMBIO.COM)
INT 26h absolute disk write (implemented in IBMBIO.COM)
INT 27h terminate and stay resident (implemented in COMMAND.COM)
CP/M CALL 0 interface (executes INT 20h)
CP/M CALL 5 interface supporting INT 21h functions 00h-24h

PC DOS 1.1 (May 1982)
developed by Seattle Computer Products and Microsoft
distributed on 1 160KB floppy disk
double-sided 320KB floppy disk support added
directory entries include the time last written in addition to the date
INT 24h vector saved in PSP
COPY supports concatenation of multiple files
new internal commands: DATE, DEL, REN, TIME
new external command: EXE2BIN
INT 21h functions 1Ch, 1Fh, 2Eh added

MS-DOS 1.25 (June 1982)
developed by Seattle Computer Products and Microsoft
first OEM version of MS-DOS (equivalent to PC DOS 1.1)
MS-DOS system files are IO.SYS and MSDOS.SYS
new external command: GWBASIC (MS-DOS only substitute for BASICA)

PC DOS 2.0 / MS-DOS 2.0 (March 1983)
developed by Microsoft
IBM developed BACKUP, FDISK, GRAPHICS, RESTORE, TREE
distributed on 2 180KB floppy disks
released with the IBM PC XT
major rewrite
subdirectory support added
volume label support added
device driver support added (device driver command codes 00h-0Ch)
file handle support added
I/O redirection support added
simple memory management and MCBs added
environment variables added (COMMAND.COM uses COMSPEC, PATH and PROMPT)
BIOS parameter block (BPB) support added
180KB single-sided and 360KB double-sided floppy disk support added
hard disk support up to 10MB (FAT12: partition type 01h)
file attributes volume label (08h), subdirectory (10h) and archive (20h) added
zero byte indicates end of directory to speed up searches
print spooler added
CONFIG.SYS (AVAILDEV, BREAK, BUFFERS, DEVICE, FILES, SHELL, SWITCHAR)
new internal commands: BREAK, CD, CHDIR, CLS, CTTY, ECHO, EXIT, FOR, GOTO, IF, MD, MKDIR, PATH, PROMPT, RD, RMDIR, SET, SHIFT, VER, VERIFY, VOL
new external commands: ASSIGN, BACKUP, FDISK, FIND, GRAPHICS, MORE, PRINT, RECOVER, RESTORE, SORT, TREE
internal character devices: AUX, CLOCK$, COM1, COM2, CON, LPT1, LPT2, LPT3, NUL, PRN
internal block device driver for disks
new device driver: ANSI.SYS
parent PSP segment, job file table and environment segment added to PSP
current directories are appended to each DPB
SYSVARS and SFT structures added
disk buffering added
INT 21h functions 2Fh-57h added
INT 21h function 4Bh (execute or load program) implemented in COMMAND.COM
INT 25h, INT 26h, INT 27h now implemented in the DOS kernel
INT 28h idle call added
INT 29h fast console output added
INT 2Eh reload transient (COMMAND.COM) added
INT 2Fh PRINT support added

MS-DOS 2.01 (May 1983)
developed by Microsoft
enhanced country support added
new external command: FC (MS-DOS)
new CONFIG.SYS command: COUNTRY
INT 21h function 38h set country info added

PC DOS 2.1 (October 1983)
developed by Microsoft
distributed on 2 180KB floppy disks
released with the IBM PCjr
PCjr half-height floppy drive support added
no enhanced country support

MS-DOS 2.11 (December 1983)
developed by Microsoft
basically PC DOS 2.1 with MS-DOS 2.01 enhanced country support and minor updates
INT 21h function 58h added

PC DOS 3.0 / MS-DOS 3.0 (August 1984)
developed by Microsoft
IBM developed GRAFTABL, KEYBFR, KEYBGR, KEYBIT, KEYBSP, KEYBUK, LABEL, SELECT, VDISK.SYS
distributed on 2 360KB floppy disks
released with the IBM PC AT
1.2MB floppy disk support added
hard disk support up to 32MB (original FAT16: partition type 04h)
redirector support added
file sharing and locking support added
date and time set from CMOS real-time clock
new external commands: ATTRIB, GRAFTABL, KEYBFR, KEYBGR, KEYBIT, KEYBSP, KEYBUK, LABEL, SELECT, SHARE
new CONFIG.SYS commands: FCBS, LASTDRIVE, STRING
CONFIG.SYS commands AVAILDEV and SWITCHAR removed
new device driver: VDISK.SYS (PC DOS only)
DOS swappable data area added
CDS and FCB-SFT structures added
job file table may be relocated via new PSP fields allowing more than 20 handles
program loading and execution now implemented in the DOS kernel
fully qualified program name added to environment block
interrupt vectors 20h-3Fh are initialized by the DOS kernel
INT 21h functions 4408h-440Bh, 59h-63h added
INT 21h functions 3702h-3703h removed
INT 2Ah networking and critical section functions added
INT 2Fh multiplex functions 01h (PRINT), 05h (REDIR error text), 10h (SHARE), 11h (REDIR), 12h (IBMDOS) added
device driver command codes 0Dh-10h added

MS-DOS 3.05 (November 1984)
developed by Microsoft
OEM version of PC DOS 3.0

PC DOS 3.1 / MS-DOS 3.1 (April 1985)
developed by Microsoft
distributed on 2 360KB floppy disks
new external commands: JOIN, SUBST
external command LABEL added to MS-DOS
CONFIG.SYS command STRING removed
SYSVARS table changed
DOS swappable data area changed (first version recognized by redirectors)
INT 21h functions 3302h, 5D07h-5D0Ah added
INT 21h function 61h removed
INT 2Fh multiplex functions 02h (REDIR print), 06h (ASSIGN) added

PC DOS 3.2 / MS-DOS 3.2 (April 1986)
developed by Microsoft
IBM developed REPLACE, XCOPY
Microsoft developed clone versions for most of the IBM developed utilities
distributed on 2 360KB floppy disks
released with the IBM PC AT model 339 and the IBM PC Convertible
first "packaged product" version of MS-DOS which OEMs could include with new PCs
720KB 3.5" floppy disk support added
hardware interrupt stack switching support added
master environment block size can be specified using COMMAND /E:size
FORMAT supports /T and /N to specify number of tracks and number of sectors
new external commands: APPEND (MS-DOS), REPLACE, XCOPY
new CONFIG.SYS commands: DRIVPARM, STACK
new device drivers: DRIVER.SYS, RAMDRIVE.SYS (MS-DOS)
INT 21h functions 440Ch-440Fh, 64h added
INT 2Fh multiplex functions 08h (IBMBIO/DRIVER.SYS), 13h (IBMBIO) added
device driver command codes 13h, 17h, 18h added

MS-DOS 3.21 (May 1987)
developed by Microsoft
distributed on 2 360KB floppy disks
maintenance release

PC DOS 3.3 / MS-DOS 3.3 (April 1987)
developed by IBM
distributed on 2 360KB floppy disks or 1 720KB floppy disk
released with the initial IBM PS/2 line
1.44MB 3.5" floppy disk support added
extended partition support (partition type 05h)
national language support added
code page switching support added
per-line batch file echo suppression added (@)
hardware interrupt stack switching support can be disabled (STACKS=0,0)
102-byte buffer reserved at 800h (70h:100h) for programs using 80286 LOADALL
ATTRIB supports /S to recurse subdirectories
new internal commands: CALL, CHCP
new external commands: FASTOPEN, KEYB, NLSFUNC
external command APPEND added to PC DOS
external commands COMP and SELECT added to MS-DOS
new internal devices: COM3, COM4
CONFIG.SYS command STACK renamed to STACKS
new device drivers: DISPLAY.SYS, PRINTER.SYS
new support files: COUNTRY.SYS, EGA.CPI, KEYBOARD.SYS
external commands KEYBFR, KEYBGR, KEYBIT, KEYBSP and KEYBUK removed (replaced by KEYB)
INT 21h functions 65h-68h added
INT 2Fh multiplex functions 14h (NLSFUNC), ADh (DISPLAY.SYS/KEYB), AEh (APPEND), B0h (GRAFTABL), B7h (APPEND) added

MS-DOS 3.31 (November 1987)
developed by Compaq (based upon MS-DOS 3.3 codebase)
distributed on 2 720KB floppy disks
hard disk support up to 2GB (enhanced FAT16: partition type 06h)
BPB extended to support 32-bit sector count
INT 25h and INT 26h extended to support greater than 32MB hard disks

PC DOS 4.0 / MS-DOS 4.0 (July 1988)
developed by IBM
distributed on 2 720KB floppy disks
FORMAT supports /F to specify disk size to format
MEM command added to report memory usage
SHARE loaded for FCB operations on hard disks greater than 32MB
IFS driver support added
new internal command: TRUENAME
new external commands: FILESYS, IFSFUNC, MEM
new CONFIG.SYS commands: COMMENT, CPSW, IFS, INSTALL, MULTITRACK, REM, SWITCHES
new device drivers: SMARTDRV.SYS (MS-DOS), XMA2EMS.SYS, XMAEM.SYS
new support file: GRAPHICS.PRO
disk buffers could be allocated in expanded memory (BUFFERS /X)
DPB, SFT and CDS structures extended
new internal version table added
DOS swappable data area changed
program names added to MCBs
system block sub-MCB headers added (used by MEM)
most commands use new message retriever which allows message text to be separate from source code for translation purposes
INT 21h functions 3305h, 5D0Bh, 5F05h-5F08h, 6507h, 6520h-6523h, 65A0h-65A3h, 69h-6Ch added
INT 21h functions 3303h-3304h, 5702h-5704h reserved but unused
INT 2Fh multiplex function 1Ah (ANSI.SYS) added

PC DOS 4.01 / MS-DOS 4.01 (August 1988)
developed by IBM
distributed on 2 720KB floppy disks
maintenance release
DOS version is reported as 4.00

PC DOS 5.0 / MS-DOS 5.0 (June 1991)
developed by Microsoft
distributed on 5 360KB floppy disks or 3 720KB floppy disks or 2 1.2MB floppy disks
first retail version of MS-DOS
first version of DOS to use a setup program
most differences between MS-DOS and PC DOS besides system filenames and copyright text are eliminated
external command FC and device drivers RAMDRIVE.SYS and SMARTDRV.SYS added to PC DOS
last version to share a common codebase, MS-DOS and PC DOS begin to diverge after 5.0
HMA support added (DOS=HIGH)
UMB support added (DOS=UMB)
2.88MB 3.5" floppy disk support added
syntax help for all commands (/?)
DIR command greatly enhanced and default switches may be set with the DIRCMD environment variable
DOSKEY command line editor added
FIND supports case-insensitive searches (/I)
FORMAT supports quick formatting allowing a disk to be unformatted
IFS driver support removed
SHARE no longer required for FCB operations on hard disks greater than 32MB
internal version table implemented in SETVER device driver
80286 LOADALL buffer removed
BUFFERS /X removed
COMMAND.COM uses the TEMP environment variable for temporary files (pipes)
EDIT replaces EDLIN
QBASIC replaces BASIC, BASICA, GWBASIC
MIRROR, UNDELETE and UNFORMAT licensed from Central Point Software PC Tools
new internal commands: LH, LOADHIGH
new external commands: DOSKEY, EDIT, EMM386, HELP, LOADFIX, MIRROR, QBASIC, SETVER, UNDELETE, UNFORMAT
new CONFIG.SYS commands: DEVICEHIGH, DOS
new device drivers: EMM386.EXE, HIMEM.SYS, SETVER.EXE
external commands FILESYS, GWBASIC, IFSFUNC, LINK and SELECT removed
CONFIG.SYS commands CPSW and IFS removed
device drivers VDISK.SYS (PC DOS), XMA2EMS.SYS and XMAEM.SYS removed
INT 21h functions 3306h, 4410h-4411h, 4B05h, 5802h-5803h added
INT 21h functions 3303h-3304h, 3701h, 5702h-5704h, 5D0Bh, 6Bh removed
INT 21h functions 6Dh-6Fh added for ROM DOS support and are only present in ROM DOS builds
INT 2Fh multiplex functions 43h (HIMEM.SYS), 48h (DOSKEY), 4Ah (IBMBIO), 55h (COMMAND), ACh (GRAPHICS) added
INT 2Fh multiplex function 122Eh moved to COMMAND.COM
INT 2Fh multiplex functions 1603h, 1605h, 1606h, 1607h, 4601h, 4602h hooked for Windows
device driver command code 19h added

MS-DOS 5.0a (November 1991)
developed by Microsoft
distributed on 5 360KB floppy disks or 3 720KB floppy disks or 2 1.2MB floppy disks
maintenance release

PC DOS 5.00.1 (February 1992)
developed by IBM (based upon MS-DOS 5.0 codebase)
distributed on 3 720KB floppy disks
maintenance release
PC DOS 5.0 revision 1

PC DOS 5.02 (September 1992)
developed by IBM (based upon MS-DOS 5.0 codebase)
distributed on 3 720KB floppy disks
new external commands: DRVLOCK, EJECT, INTERLNK, INTERSVR, MOUSE, POWER
new device drivers: CMOSCLK.SYS, INTERLNK.EXE, POWER.EXE
new support files: EGAX.CPI, ISO.CPI
INT 2Fh multiplex functions 54h (POWER) and 56h (INTERLNK) added

MS-DOS 6.0 (March 1993)
developed by Microsoft
distributed on 3 1.44MB floppy disks
startup menu added
DoubleSpace disk compression added
INTERLNK, INTERSVR and POWER added from PC DOS 5.02
SMARTDRV.EXE replaces SMARTDRV.SYS
disk defragmenter added (licensed version of Speed Disk from Norton Utilities)
MS backup added
MS anti-virus added
new external commands: CHOICE, DEFRAG, DELTREE, MOVE, MSCDEX, MSD, SMARTDRV
new CONFIG.SYS commands: INCLUDE, INSTALLHIGH, MENUCOLOR, MENUDEFAULT, MENUITEM, NUMLOCK, SET, SUBMENU
external command RECOVER removed
INT 2Fh multiplex function 15h (MSCDEX) added

PC DOS 6.1 (June 1993)
developed by IBM (based upon MS-DOS 6.0 codebase)
distributed on 4 1.44MB floppy disks
many optimizations
includes most new features of MS-DOS 6.0 except DoubleSpace, MS backup, MS anti-virus and MSD
PCMCIA utilities added
PenDOS utilities added
Central Point backup added
Central Point scheduler added
IBM anti-virus added
E editor replaces EDIT
QCONFIG replaces MSD
new external commands: DATAMON, E, QCONFIG
external commands BASIC, BASICA and MIRROR removed
DOS version is reported as 6.00

MS-DOS 6.2 (September 1993)
developed by Microsoft
distributed on 3 1.44MB floppy disks
CHKDSK, DIR, FORMAT and MEM display numbers with separators
COPY, MOVE and XCOPY prompt before overwriting files unless /Y is used (may be set via the COPYCMD environment variable)
DoubleSpace disk compression enhanced
new external command: SCANDISK

MS-DOS 6.21 (February 1994)
developed by Microsoft
distributed on 3 1.44MB floppy disks
DoubleSpace removed due to injunction from Stac Electronics lawsuit
DOS version is reported as 6.20

MS-DOS 6.22 (May 1994)
developed by Microsoft
distributed on 3 1.44MB floppy disks
DriveSpace disk compression added (replacing DoubleSpace)

PC DOS 6.3 (April 1994)
developed by IBM (based upon PC DOS 6.1 and MS-DOS 6.2 codebases)
distributed on 5 1.44MB floppy disks
last version of PC DOS to incorporate code from MS-DOS
CHKDSK, DIR, FORMAT and MEM display numbers with separators unless the NO_SEP environment variable is set
COPY, MOVE and XCOPY prompt before overwriting files unless /Y is used (may be set via the COPYCMD environment variable)
SuperStor disk compression added

PC DOS 7.0 (April 1995)
developed by IBM
distributed on 5 1.44MB floppy disks (disks 2-5 are in XDF format)
many optimizations
DOS tables can load into upper memory (DOSDATA=UMB)
COMMAND.COM can load into upper memory (/H)
DISKCOPY can use XMS for copying disks in systems with one floppy drive
DOSKEY and SHARE can load part of their resident code into the HMA
DYNALOAD command added to load device drivers from the command line
FIND supports filenames with wildcards and /S to search subdirectories
HIMEM.SYS supports fast A20 handler
PROMPT $P$G set by default
REXX interpreter added
Stacker disk compression added (replacing SuperStor)
new external commands: ACALC, DYNALOAD, REXX, REXXDUMP
new CONFIG.SYS command: DOSDATA
external commands COMP, EDLIN, EXE2BIN, FASTOPEN, GRAFTABL and GRAPHICS removed
device driver PRINTER.SYS removed

MS-DOS 7.0 [Windows 95] (August 1995)
developed by Microsoft
not standalone, part of Windows 95
system files IO.SYS and MSDOS.SYS are merged into a single IO.SYS file
new MSDOS.SYS configuration file
COMMAND.COM now in EXE format
new internal commands: LFNFOR, LOCK, UNLOCK
new CONFIG.SYS commands: ACCDATE, BUFFERSHIGH, FCBSHIGH, FILESHIGH, LASTDRIVEHIGH, STACKSHIGH
new device driver: OAKCDROM.SYS
INT 21h functions 3307h, 5704h-5705h, 6500h, 70h, 7300h-7301h added
INT 21h functions 5706h-5707h, 71h, 72h added (VDM only)

MS-DOS 7.1 [Windows 95 OSR2] (August 1996)
developed by Microsoft
not standalone, part of Windows 95 OSR2, Windows 98 and Windows 98 SE
greater than 2GB hard disk support (LBA and FAT32: partition types 0Bh, 0Ch, 0Eh, 0Fh)
BPB and DPB extended for FAT32
INT 21h functions 7302h-7305h added

PC DOS 2000 (April 1998)
developed by IBM
distributed on 6 1.44MB floppy disks or 1 CD
PC DOS 7.0 revision 1
Y2K support for systems without proper century rollover handling
support added for Euro currency symbol

PC DOS 7.1 (1999)
developed by IBM
not released as a retail product, multiple revisions between 1999 and 2003
original build: 1999
build 1.10: August 2000
build 1.11: January 2001
build 1.19: July 2002
build 1.26: March 2003
build 1.28: July 2003
build 1.29: September 2003
build 1.32: December 2003
based upon PC DOS 2000
greater than 2GB hard disk support (LBA and FAT32: partition types 0Bh, 0Ch, 0Eh, 0Fh)
BPB and DPB extended for FAT32
INT 21h functions 3307h, 5704h-5707h, 6500h, 70h, 7300h-7305h added

MS-DOS 8.0 [Windows ME] (September 2000)
developed by Microsoft
not standalone, part of Windows ME
modified to restrict access to real mode DOS
HIMEM functionality merged into IO.SYS
IO.SYS is compressed