See pages 502-503 of this scan: Poorly scanned, but I recognise the table. It's the "old" book of that name, not the "new" one. Near the back there was a two page table containing a dense opcode map (the byte values) of the 6502, its mnemonics, and a tiny notation hinting what they might do. That's the one with all those VDU codes and ∗FX commands. I didn't have many books, but I did have the BBC Advanced User Guide. I learned everything about that virus, and later about others. I was merely 14 years old, and spent a whole summer doing things like that, while other kids were doing whatever other kids normally do. At some point I got Turbo Debugger too, that made things so much easier. I wish I still had my notes from back then. So I set myself to reverse engineer this virus (I had no idea it’s called reverse engineering), by using the old (or was it exe?) that came with DOS.
I had and loved F-Prot antivirus for its database of virus descriptions. By that time I had access to BBS through some friends, and I got to download various docs about assembler and so on. On this machine I encountered the first computer virus, named Romania.856. It came with some early DOS and GEM desktop environment. Oh, right, and it had a big, loud, slow 20MiB HDD. Later on, I got a second hand 8086 based PC, which came with a full setup: central unit, display (monochrome), keyboard and mouse, and 5.25” floppy disk drive. This was a lifetime ago, I hope what I remember is correct. Because I didn’t have a tape drive for it, I was writing entire programs and then write them down on paper, and “reload” them after the computer would reset, or if I were lucky, just the next day.Īt one point I figured out the opcodes for Z80 were at the end of the somewhat thin manual, and that I can read/write straight into memory.
When I was 12, I had a Romanian Z80 based computer, that would run BASIC.
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