Booting Every Single DOS Version & Checking The Free Conventional Memory So You Don’t Have To
I booted every single version of MS-DOS and IBM PC-DOS in VirtualBox using modified images from WinWorld, and ran the chkdsk command to see how much conventional memory was available. These have had their autoexec.bat and config.sys files either deleted or cleared, so there were no TSRs taking up memory in the background.
Note that results under other emulators and on real hardware may vary, but will be relatively the same and in the same ballpark. This is something that I hope to delve into in more detail in future updates to this page.
MS-DOS
| Version | Bytes Total | Bytes Free | Bytes Used | Notes |
|---|---|---|---|---|
| 3.30 | 654,336 | 599,360 | 54,976 | |
| 3.31 | 654,336 | 598,384 | 55,952 | Support for HDD partitions over 32MB |
| 4.00 | 655,360 | 563,088 | 92,272 | |
| 4.01 | 655,360 | 569,296 | 86,064 | |
| 4.01c | 655,360 | 588,464 | 66,896 | |
| 5.00 | 655,360 | 583,280 | 72,080 | MS-DOS Editor (EDIT.COM) and QBasic added |
| 5.00a | 655,360 | 583,280 | 72,080 | Bugfix release for the above |
| 6.00 | 655,360 | 582,192 | 73,168 | New disk utlities, DoubleSpace disk compression |
| 6.20 | 655,360 | 581,472 | 73,888 | |
| 6.21 | 655,360 | 581,472 | 73,888 | DoubleSpace removed |
| 6.22 | 655,360 | 581,472 | 73,888 | DriveSpace added |
IBM PC-DOS
| Version | Bytes Total | Bytes Free | Bytes Used | Notes |
|---|---|---|---|---|
| 1.00 | 654,336 | 642,192 | 12,144 | |
| 1.10 | 654,336 | 641,936 | 12,400 | Double sided disk support |
| 2.00 | 654,336 | 629,648 | 24,688 | Hard Disk Drives, subdirectories, device drivers |
| 2.10 | 654,336 | 629,648 | 24,688 | |
| 3.00 | 654,336 | 615,440 | 38,896 | Support for larger disks |
| 3.10 | 654,336 | 615,408 | 38,928 | Networking support |
| 3.20 | 654,336 | 608,368 | 45,968 | 3.5” 720K floppy support |
| 3.30 | 654,336 | 599,504 | 54,832 | 3.5” 1.44MB floppy support, extended partitions |
| 4.00 | 655,360 | 564,656 | 90,704 | DOS Shell, EMS 4.0 support |
| 4.10 | 655,360 | 564,640 | 90,720 | |
| 5.00 | 655,360 | 583,248 | 72,112 | |
| 5.00.1 | 655,360 | 583,232 | 72,128 | |
| 5.02 | 655,360 | 581,696 | 73,664 | |
| 6.1 | 655,360 | 590,768 | 64,592 | First version after split with MS |
| 6.3 | 655,360 | 590,752 | 64,608 | SuperStor Disk Compression added |
| 7.0 | 655,360 | 591,568 | 63,792 | Memory optimizations, Stacker disk compression, Rexx |
| 2000 | 655,360 | 591,488 | 63,872 |
My Opinion
If you are looking for a “modern” DOS for old machines, with support for large drives and networking but a 3.x-4.x era memory footprint, go for IBM PC-DOS 2000. I run it on my IBM 5150 with 640K of RAM with no issues.
Personally, I would not recommend any version of DOS lower than PC-DOS 3.30 / MS-DOS 3.31 unless you can live with the severe limitations with regard to disk support. I also wouldn’t recommend any version of 4.x, as it is notoriously buggy.
For anything 386-era and above, you may also want to consider the FreeDOS project.
If you liked this post please consider following me on Instagram or Twitter!
