This was a major upgrade. It allowed parts of DOS to load itself in the high memory area and certain device drivers and TSRs to run in the unused parts of the upper memory area between 640K and 1024K. This version also added support for IBM’s new 2.88 MB floppy disks. An improved BASIC interpreter and text editor were included, as was a disk cache, an undelete utility and a hard-disk partition-table backup program. After the problems with MS-DOS 4, it also provided a utility to make programs think they were running on a different version of MS-DOS.
5 1/4 inch
Support for XMS (Extended), EMS (Expanded) and HMA memory was added.
It was also shipped with the new DOS-Shell and a more comfortable editor and this is the first version which could update older versions.
Also a version 5.0a was release – this was a minor bug fix which dealt with possibly catastrophic problems with UNDELETE and CHKDSK.