There is a very old polish antivirus program (called MKS_VIR) for DOS. Its value is not that it detect viruses, because it was created in '90 and its databases are out of date, but because it has built-in virus lexicon. It consists of very good descriptions of many viruses. Those viruses created in the '80 and '90 (for DOS 1.0, 2.0, etc) had built-in speccial effects (like playing some songs on PC-Speaker, displaying various things on screen, rotating the font, etc) that were shown to the user for example on anniversaries. The examples of those demos are available to see in this program.
The author of this software was a tallented Polish programmer - Marek Sell (He is not alive now).
Howewer, running this program on DOSBOX fails - after running it tries to scan memory for the presence of viruses and hangs on the screen and waits forever. Is this a dosbox bug? I think this program can do some unconventional things with processor and/or memory so that might be the reason.
Szukam wirusow zainstalowanych w pamieci operacyjnej komputera
in translation from Polish means
Searching for virusses installed in computer memory
Im publishing this program for download.