The history of DOS (Disk Operating System) goes back to 1981 and the advent of the IBM PC. Microsoft was asked to make a operating system for IBM. This new operating system was known as PC DOS. DOS was made to be able to load other software programs designed on a standard operating system. MS DOS is similar to PC DOS except for the hidden files that work with the firm ware of the PC to interpret the hardware and software drivers.
| DOS TYPE AND VERSION |
DATE | COMMAND.COM | IO.SYS or IBMBIO.COM |
MSDOS.SYS or IBMDOS.COM |
|---|---|---|---|---|
| PC 1.0 | 8-4-81 | 3,231 | 1,920 | 6,400 |
| MS 1.0 | 8-4-81 | 3,231 | 1,920 | 6,400 |
| PC 1.1 | 5-7-82 | 4,959 | 1,920 | 6,400 |
| PC 2.0 | 3-8-83 | 17,792 | 4,608 | 17,152 |
| MS 2.0 | 3-8-83 | 17,792 | 4,608 | 17,152 |
| PC 2.1 | 10-20-83 | 17,792 | 4,736 | 17,024 |
| MS 2.11 | 11-17-83 | 15,957 | 6,836 | 17,176 |
| PC 2.11 | 5-30-84 | 18,272 | 5,120 | 17,408 |
| PC 3.0 | 8-14-84 | 22,042 | 8,964 | 27,920 |
| MS 3.0 | 8-14-84 | 22,042 | 8,964 | 27,920 |
| PC 3.1 | 3-7-85 | 23,210 | 9,564 | 27,760 |
| MS 3.1 | 3-7-85 | 23,210 | 9,564 | 27,760 |
| PC 3.2 | 12-30-85 | 23,791 | 16,369 | 28,477 |
| MS 3.2 | 7-7-86 | 23,612 | 16,138 | 28,480 |
| MS 3.21 | 5-1-87 | 23,948 | 18,501 | 28,480 |
| PC 3.3 | 3-17-87 | 25,307 | 22,100 | 30,159 |
| MS 3.3 | 7-24-87 | 25,276 | 22,357 | 30,128 |
| MS 3.3a | 2-2-88 | 25,308 | 22,398 | 30,128 |
| MS 4.0 | 10-6-88 | 37,254 | 32,874 | 36,903 |
| MS 4.01 | 11-30-88 | 37,396 | 33,173 | 37,180 |
| PC 4.01 | 4-3-89 | 37,396 | 33,173 | 37,180 |
| MS 4.01a | 4-7-89 | 37,557 | 33,337 | 37,376 |
| MS 5.0 | 4-9-91 | 33,430 | 37,394 | 47,845 |
| PC 5.0 | 5-9-91 | 47,987 | 33,430 | 37,378 |
| PC 5.001a | 2-28-92 | 48,006 | 33,446 | 37,378 |
| PC 5.02 | 9-1-92 | 47,990 | 33,718 | 37,362 |
| MS 6.0 | 3-10-93 | 52,925 | 40,470 | 38,138 |
| IBM 6.1 | 6-29-93 | 52,589 | 40,964 | 38,138 |
| PC 6.1 | 9-30-93 | 52,797 | 40,964 | 38,138 |
| MS 6.2R0 | 9-30-93 | 54,619 | 40,566 | 38,138 |
| MS 6.22 | 5-31-94 | 54,645 | 40,774 | 38,138 |
| PC 6.3 | 12-31-93 | 54,654 | 40,758 | 37,174 |
Note: Microsoft had no official version of MS DOS prior to DOS 3.2. Only OEM ( Original Equipment Manufacturer ) versions were sold with the PC by the computer manufacture.
This guide is just for reference. There may be a slight variation in size of the files if you are using OEM, MS DOS.