Analysis of information sources in references of the Wikipedia article "Comparison of DOS operating systems" in English language version.
6.22 and 7.1 kernels
FORMAT /S command, that can be substituted by formatting HDD/FDD and then copying IO.SYS from CD-ROM boot A: image, as first ever file onto drive; loss of SYS A: (or SYS B:) command for floppies, that can be substituted too in the same way as FORMAT /S; inability to boot to a command prompt without substitution/modification of IO.SYS (other than CD-ROM boot version) and COMMAND.COM. For purpose of booting from C: drive, an unmodified IO.SYS from simulated A: boot diskette image, that is placed on Windows Me OEM CD-ROM, from which that CD boots, can be used, and English COMMAND.COM can be modified by replacing in this file at hex offset 00006510h byte 75h by byte EBh, or substituted by (now freeware) 4DOS http://www.jpsoft.com/download.htm Archived 2006-09-01 at the Wayback MachinePTS-DOS 32 [..] Memory Manager himem.sys, included in PTS-DOS 32, supports up to 4 GB of RAM.
PTS-DOS 2000 [..] PTS-DOS is a powerful and fast 16-bit disk operating system, fully compatible with MS-DOS and all its applications.
FORMAT /S command, that can be substituted by formatting HDD/FDD and then copying IO.SYS from CD-ROM boot A: image, as first ever file onto drive; loss of SYS A: (or SYS B:) command for floppies, that can be substituted too in the same way as FORMAT /S; inability to boot to a command prompt without substitution/modification of IO.SYS (other than CD-ROM boot version) and COMMAND.COM. For purpose of booting from C: drive, an unmodified IO.SYS from simulated A: boot diskette image, that is placed on Windows Me OEM CD-ROM, from which that CD boots, can be used, and English COMMAND.COM can be modified by replacing in this file at hex offset 00006510h byte 75h by byte EBh, or substituted by (now freeware) 4DOS http://www.jpsoft.com/download.htm Archived 2006-09-01 at the Wayback Machine