My father bought me an Pravetz 8C computer (well Apple IIc clone) -
http://www.old-computers.com/museum/computer.asp?st=1&c=1057 - also
http://www.pravetz.info/pravetz-8c.html (in bulgarian). It costed 1500 levas which were a lot of money back then.
Now there was no official software, books, etc. to be found in Bulgaria. There were some really good books though, and 1 or 2 magazines that were putting ONE-LINE basic programms, or HEX codes for the Apple][ or Oric clones (called Pravetz 8D)
With a friend of mine (who had the 8D version, e.g. the Oric clone, not Apple) we spent a lot of time entering these codes and then comparing the machines. His "Oric" was pluggable into TV set, had better colors, and used tape. Mine had floppy, more memory, but greenish monitor (no colors), although high-res (Apple ][c had the 580x192 back then).
He had timers, interrupts, multiple keys at the same time, I did not had those :)
I did my first hack, out of being bored to make the live in the Gemstone Warrior game never end. There was this TSR application (TSR=terminate and stay resident) on the PC (MS-DOS) with which you can save the full memory of your computer. So if you play a game, you would save the memory before you die, then save after you die. You do this several times. Most of the memory would be untouched, so you would be looking where the bytes would decrease (some PC games actually used BIC encoding, e.g. integers kept as strings). But once I've got the idea, I've did some hacks to interrupt the Apple ][ Gemstone Warrior game, write back to the floppy the contents, and then spent days writing code to find the diffs. At the end I had to look at so much assembly, that by accident I've found how to make infinite lifes in the game.
So a lot of CALL-151, but never learned 6502 assembly that well. I was amazed when a friend of ours showed us a sprite demo where he could draw the sprites on the edges of the screen (!!!!) and displayed on every pixel on the screen (not aligned on 7). That was bananas! Also his demo did not had any flickering, and all coded in assembly.... I had to stay in BASIC land for a while, eventually made an text-editor that was mimicking the E3 editor found on the PC - with scrolling left-right. It was written in BASIC and took most of the memory, leaving almost nothing for the actual text :) - but hey it was fun.
There was this strange person though, he wrote a whole BASIC app - about 15-20kb full of LINE code (HGR, HGR2 modes) drawing Michael Jackson (okay, no Take 2, Paint shop - it was Michael Jackson drawn by code line by line).
Year later we started getting tons of "illegal" (as there was nothing else) software and enjoying lots of other games.
One day my floppy died. Months earlier my friend with the Oric had bought an external floppy, but it died also, so he found a way to seek from the begining of the head to the end and control it with the shift keys, then he assigned letters to correspond to different seek, and it sounded a bit like piano.
I did the same on my floppy when it was no good for anything else, but wasn't as cool - no shifts, just rumbling.
Ah, sector 11, or was it track 11... The memories....