- Major revision, 1983.
- Introduced with the IBM XT, OEM IBM Corporation PC-DOS.
- OEM Zenith Computer Corporation.
- Added support for 80-115ms 10M hard disk.
- Added 9-sector (360K) capability to 2-sided (double-sided)
- Added UNIX-like tree-structured (hierarchical) directory
- DOS uses slash (/) as the switch character, backslash (\) to
separate subdirectory levels;
UNIX uses dash (-) as the switch character, slash (/) to
separate subdirectory levels.
- Added concept of Standard I/O and re-direction + DOS
- Added the ability to install ANSI.SYS and non-standard device
drivers via new CONFIG.SYS.
- Improved BASIC with extended graphics commands, I/O
- Added simple multitasking, using memory-resident programs
(AKA Terminate-and-Stay-Resident, TSR) PRINT and GRAPHICS.
- Handle-Oriented File I/O superceded the hard-to-use
file-control-block (FCB) File I/O to simplify file/device
- DOS function 1bH stopped returning a pointer to the actual
FAT and just returns a pointer to a media descriptor byte.
- Commands introduced:
- Commands enhanced: