86-DOS Version 0.11 Found (opens in new tab)

What got me into assembly programming was my peecee getting infected with the STONED virus at the end of the 80's. DOS came with a small very thick binder user manual, and the DEBUG.EXE section was very extensive. It seemed to me that I could use it to repair my disks. It took a while, but I succeeded.

I managed to carve out the boot sector, learn assembly, and rewrite the virus code to more human readable format, and then the cherry on top: read the original boot sector off the disk (which I learned about through the virus code itself) and write it on top of the virus code. All this just from the user manual pages for DEBUG. The code for both reading and writing the virus code and the original boot sector, which was offset to a different sector, was right there in the virus. So it was an unusual self-documenting solution.

That was so much fun, I went head first into learning how to program in Assembler using TASM (Borland Turbo Assembler), which is in every way a more friendly way to write assembler. I still have the TASM programming book I bought way back then on my severely nerdy book shelf.

Those sure were the days.

Unsurprisingly, I kept up on viruses and antivirus, then hacking, then firewalls, then pentesting, in that order, as they were invented. The STONED virus and the DOS manual literally gave me a career path.

Yea, I think you could only write a COM file, since they are single segment "memory images". And 64kB was indeed the limit for a memory segment in those days.

Depending on what you were doing, even a ^C character in a script would throw it off, too.