DOS Versions (Was: IBM PC-DOS 2.10 explorations

On Sun, 4 Oct 2020, Richard Cini wrote: PS/2 came out with PC-DOS 3.30 But also an IBM push for OS/2 DOS versions according to media support (ignoring other IMPORTANT changes, such as file handles, hierarchical DIRectories, etc.) DOS 1.00 160k 40 tracks single sided 8 sectors per track. PC-DOS 1.10 MS-DOS 1.25 320K 40 tracks per side double sided 8 sectors per track. DOS 2.00 360K 9 sectors per track MS-DOS 2.11 customized by SOME OEMs 720K 3.5"; not all are same format as PC-DOS! DOS 3.00 1.2M DOS 3.10 CD-ROM "network redirector" DOS 3.20 720K DOS 3.30 1.4M MS-DOS 3.31 HDD >32M customized by OEMs PC-DOS 4.00 MS-DOS 5.00 first version sold RETAIL MS-DOS 6.00 PC-DOS 6.10 cartload of bundled third party add-ons MS-DOS 6.20 patched for reliability, including changing SMARTDRV to stop trashing disks (blamed on compression) MS-DOS 6.21 compression not provided (copyright lawsuit) MS-DOS 6.22 non-infringing compression Win98SE USB Note that 2.11 and 3.31, due to OEM customization will OFTEN have a different FORMAT program (different drives), and different MODE.COM (some had different video modes available). Sometimes some other bundled programs had differences. Note that DOS version is a numeral, a period, then a two digit decimal number. It is ALWAYS 2.10, NOT 2.1; 3.10, NOT 3.1, etc. What we call 2.1 is ACTUALLY version TWO point TEN! what we call 3.2 is ACTUALLY version THREE point TWENTY! what we call 3.31 is ACTUALLY version THREE point THIRTY-ONE! what we call 4.01 is actually version FOUR point ONE. MOV AH, 30h INT 21h returns the major version in AL. Print that. Then print a period. Minor version is in AH. print that as a 2 digit decimal number. 2.10 has AX: 0A02 3.10 has AX: 0A03 3.20 has AX: 1403 3.30 has AX: 1E03 3.31 has AX: 1F03 Note: SETVER (since 5.00) lets a version of DOS lie about its age. There's an important reason. When PC-DOS 1.10 came out, with double sided drives, people sometimes ran CHKDSK from DOS 1.00 (sometimes even having 1.00 CHKDSK on a 1.10 boot disk), which proceeded to "FIX" the disk into an unusable form. To prevent that and similar disasters, in addition to modifying CHKDSK to not make changes without confirmation, henceforth, EVERY program distributed with DOS had a MOV AH,30h/INT21h/CMP AX... so that programs could only run with "correct version of DOS. When they stopped including EXE2BIN.EXE and even LINK.EXE with DOS, it became necessary to either step on the version checking code (with DEBUG.COM) or use SETVER. I'll do a separate post about DRIVER.SYS and DRIVPARM. -- Grumpy Ol' Fred cisin at xenosoft.com