DOS Abandonware
MSDOS 7.10
There has been a need for me to resurrect older machines in order to program Motorola radios lately and I had quite a struggle locating older copies of ms-dos, windows, etc. I have located several resources and all of the files here (and those that are linked) are officially abandonware, or have been placed in the public domain by their respective copyright owners.
I highly recommend this source. I have tested the files and they're fine. See http://ms-dos7.hit.bg/ They deserve the credit for hosting this stuff. Meanwhile, in case something happens to that site, here is the ISO image for MS-DOS 7.10 (bootable) see …
I chose MS-DOS 7.10 because it's now in the public domain (Microsoft has released the source code as well) and it's "more compatible" than FreeDOS which still seems to have some odd bugs. While programming a radio if I get some kind of "glitch" I risk destroying the radio so I'm quite content to use MS-DOS 7.10 as opposed to FreeDOS.
I have been able to successfully dual-boot MSDOS 7.10 and Debian Linux (grub handling the boot) so don't waste a perfectly good machine on MSDOS, use a dual-boot setup at least!
Utilities
ARJ file archiver/extractorDOS MD5 utility
Norton Commander (DOS) Abandonware
RAR file extractor/archiver DOS
ZOO file extractor/archiver DOS
PKZIP file extractor/archiver DOS