MS-DOS 4.01 --- The PCjs machine below is running PC-DOS 4.01. [IBM Model 5170](machine.xml "PCjs:ibm5170-msdos401") Vital Statistics --- MS-DOS 4.01 was released in April, 1989. The contents of the six 360Kb distribution diskettes are shown below. ***DISK 1*** Volume in drive A is INST V401 Volume Serial Number is 2A33-13E4 Directory of A:\ IO SYS 33337 04-07-89 12:00a MSDOS SYS 37376 04-07-89 12:00a AUTOEXEC BAT 39 04-07-89 12:00a COMMAND COM 37557 04-07-89 12:00a CONFIG SYS 96 04-07-89 12:00a COUNTRY SYS 12806 04-07-89 12:00a DISKCOPY COM 10396 04-07-89 12:00a DISPLAY SYS 15692 04-07-89 12:00a FDISK EXE 60935 04-07-89 12:00a FORMAT COM 22875 04-07-89 12:00a KEYB COM 14727 04-07-89 12:00a KEYBOARD SYS 23328 04-07-89 12:00a REPLACE EXE 19415 04-07-89 12:00a SELECT COM 3642 04-07-89 12:00a SELECT HLP 28695 04-07-89 12:00a SELECT PRT 1329 04-07-89 12:00a SYS COM 11456 04-07-89 12:00a 15 File(s) 18432 bytes free ***DISK 2*** Volume in drive A is OP#1 V401 Directory of A:\ ASSIGN COM 5753 04-07-89 12:00a ATTRIB EXE 18263 04-07-89 12:00a CHKDSK COM 17787 04-07-89 12:00a COMMAND COM 37557 04-07-89 12:00a COMP COM 9459 04-07-89 12:00a DEBUG COM 21574 04-07-89 12:00a DISKCOMP COM 9857 04-07-89 12:00a EDLIN COM 14069 04-07-89 12:00a FC EXE 15807 04-07-89 12:00a FILESYS EXE 11129 04-07-89 12:00a FIND EXE 5941 04-07-89 12:00a IFSFUNC EXE 21739 04-07-89 12:00a JOIN EXE 17813 04-07-89 12:00a LABEL COM 4458 04-07-89 12:00a MEM EXE 20005 04-07-89 12:00a MORE COM 2134 04-07-89 12:00a SHARE EXE 13424 04-07-89 12:00a SORT EXE 5882 04-07-89 12:00a SUBST EXE 18467 04-07-89 12:00a TREE COM 6302 04-07-89 12:00a XCOPY EXE 17055 04-07-89 12:00a 21 File(s) 56320 bytes free ***DISK 3*** Volume in drive A is OP#2 V401 Directory of A:\ COMMAND COM 37557 04-07-89 12:00a EMM386 SYS 87776 04-07-89 12:00a EXE2BIN EXE 7963 04-07-89 12:00a GWBASIC EXE 80608 04-07-89 12:00a LINK EXE 43988 04-07-89 12:00a PRINT COM 14131 04-07-89 12:00a RAMDRIVE SYS 8235 04-07-89 12:00a README TXT 17825 04-07-89 12:00a SMARTDRV SYS 10224 04-07-89 12:00a XMA2EMS SYS 29211 04-07-89 12:00a 10 File(s) 21504 bytes free ***DISK 4*** Volume in drive A is OP#3 V401 Volume Serial Number is 2A33-13E4 Directory of A:\ 4201 CPI 6404 04-07-89 12:00a 4208 CPI 720 04-07-89 12:00a 5202 CPI 370 04-07-89 12:00a ANSI SYS 9105 04-07-89 12:00a APPEND EXE 11154 04-07-89 12:00a COMMAND COM 37557 04-07-89 12:00a COUNTRY SYS 12806 04-07-89 12:00a DISPLAY SYS 15692 04-07-89 12:00a DRIVER SYS 5241 04-07-89 12:00a FASTOPEN EXE 16718 04-07-89 12:00a GRAFTABL COM 10239 04-07-89 12:00a GRAPHICS COM 16693 04-07-89 12:00a GRAPHICS PRO 9397 04-07-89 12:00a HIMEM SYS 6261 04-07-89 12:00a KEYB COM 14727 04-07-89 12:00a KEYBOARD SYS 23328 04-07-89 12:00a MODE COM 22960 04-07-89 12:00a NLSFUNC EXE 6878 04-07-89 12:00a PRINTER SYS 18914 04-07-89 12:00a RAMDRIVE SYS 8235 04-07-89 12:00a RECOVER COM 10588 04-07-89 12:00a 21 File(s) 15360 bytes free ***DISK 5*** Volume in drive A is SELECT V401 Directory of A:\ BACKUP COM 36880 04-07-89 12:00a EGA CPI 49068 04-07-89 12:00a FORMAT COM 22875 04-07-89 12:00a LCD CPI 10703 04-07-89 12:00a MODE COM 22960 04-07-89 12:00a RESTORE COM 36946 04-07-89 12:00a SELECT DAT 22999 04-07-89 12:00a SELECT EXE 95107 04-07-89 12:00a XMA2EMS SYS 29211 04-07-89 12:00a 9 File(s) 30720 bytes free ***DISK 6*** Volume in drive A is SHELL V401 Directory of A:\ CHKDSK COM 17787 04-07-89 12:00a COMMAND COM 37557 04-07-89 12:00a DISKCOPY COM 10396 04-07-89 12:00a DOSUTIL MEU 6660 04-07-89 12:00a PCIBMDRV MOS 263 04-07-89 12:00a PRINT COM 14131 04-07-89 12:00a SHELL HLP 66527 04-07-89 12:00a SHELL MEU 4588 04-07-89 12:00a SHELL CLR 4406 04-07-89 12:00a SHELLB COM 3894 04-07-89 12:00a SHELLC EXE 153855 04-07-89 12:00a 11 File(s) 36864 bytes free One important new feature of MS-DOS 4.01 was the ability to update the system files (IO.SYS and MSDOS.SYS) of any boot disk, by moving the first two directory entries (and the contents of the first three data sectors) as needed to make room for the new IO.SYS and MSDOS.SYS files. The SYS command in older versions of MS-DOS would report "No room for system on destination disk" if the first two directory entries (or the first three data sectors) were unavailable. However, after using the MS-DOS 4.01 SYS command, it usually becomes possible to install older MS-DOS versions as well. Learn more about the history of the SYS command from [Microsoft Support](https://support.microsoft.com/en-us/kb/66530). Additional details about MS-DOS 4.01 from [PC DOS Retro](https://sites.google.com/site/pcdosretro/doshist): - distributed on 2 720KB floppy disks [or 6 360KB diskettes] - maintenance release - DOS version is reported as 4.00 [although the VER command reports "4.01"] - SHARE loaded for FCB operations on hard disks greater than 32MB - IFS driver support added - MEM command added to report memory usage - 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 - 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