Weak sectors on CDs

Here is a very good explanation of the weak sector problem on CDs:
http://ixbtlabs.com/articles2/magia-chisel/. It is used in some copy protection schemes like SafeDisc. It reminded me of weak data I produced on the C64 where GCR-encoding  was done in software. So you could easily write something that is not well formed. Doing this led to sectors that contained different data every time you read them. Very funny. And confused every copy program I know of.

Blitter kills

The Amiga was an absolutely marvellous  machine. It had so fantastic special hardware for that time. It was incredible. Two of them where Copper and Blitter. A funny trick to hinder the debugger was to set up the Copper to tell Blitter to fill the memory of your running program with 0x00 the next time the cathode ray reaches a specific position. Your program regularly stopped the Copper from doing this. But if you stopped the CPU with a debugger, Copper and Blitter continue there work and killed your programm or other important things.

Borland C's affair with the Amiga

That was a very funny project of mine at that time. The point was that I was very excited about Borlands C-Compiler for the Atari-ST. It produced 68000-Code that was way better than any other Compiler for the Amiga. It didn't produce assembler text files but binary code directly. So the compiler was fast as well. So decided to port it to the Amiga. Well, I had no source code. I converted to compilers Object format, wrote a wrapper that handled the traps used on Atari's GEM and emulated them as needed. I thought the first trap would open the source file. Wrong! The first trap read the system time to initialise __DATE__ and __TIME__ macros.  I patched the routine that produced the object file to produce the symbol table, relocation information and so on in the Amiga format.
After everything was working I went on the next CEBIT to the Borland booth and looked for someone with no tie (you know the techies). I told him what I did and asked him if they would want to sell there compiler to Amiga market. He said "No", because they would have to support it and they didn't want to go into the Amiga market. But they wouldn't bother if I would sell this add-on as long as the original compiler is still needed.
Well, I didn't do that and so it was just used by very few people.

Early warnings

Once upon the time I was browsing through a book which disassembled the Amiga Kickstart-ROM (well I don't remember it's name but it was long before the very nice Amiga Guru-Buch came out). What I saw there, immediately caught my  attention. If the filesystem on a new mounted filesystem had a specific problem it would try to load a program to fix it. The interesting point was, that it first tried to load from that filesystem! If it couldn't find it there it tried the system-partition. Some hours later I had a floppy that upon inserting it into your Amiga immediately showed a very nice custom Guru-Meditation. I showed this floppy to a friend of mine who was astonished as well because the Amiga had no known feature to automatically start a program upon inserting a floppy. It was very hard to keep it from starting it. Luckily viruses where more a theoretic thing at that time. We had copy protection on our mind. It would be very funny to start the game immediately upon inserting the disk.

WX

I just remember that the Motorola 68000 build into the ATARI-ST had a very small cache. It could be used for a funny trick to hinder the debugger. If you just wrote the next instruction with a move the 68000 executes the instruction that was there before. But if you used a debugger you would execute the new instruction. Obviously you had to make sure that no interrupts occurred.

C64 on steroids

In the early 80th I codeveloped with Klaus Roreger the Floppy-Speeder Professional-DOS. See
http://www.d81.de/ProfessionalDOS/Hardware/roms.shtml
I don't remember the exact timeframe. It must have been before 1985. Wow that was really funny. I remember looking "alien" for the first time and talking with Klaus Roreger about how to get around this (at that time) expensive bit shifting. So we came up with the idea of a latch that is automatically filled with current low order 4-Bit and could be used in the next access. See http://www.d81.de/ProfessionalDOS/Hardware/electronic.shtml#Function. It was really funny to read this after all those years. And some guys really put very much energy into documenting it. We had no debugger at that time to debug the C1541. No emulator for the hardware. Just do it. Developing software got so much easier today.