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Programming the Commodore 64: the Definitive Guide
Mirk writes "Back in 1985 it was possible to understand the whole computer, from the hardware up through device drivers and the kernel through to the high-level language that came burned into the ROMs (even if it was only Microsoft BASIC). The Reinvigorated Programmer revisits R. C. West's classic and exhaustive book Programming the Commodore 64 and laments the decline of that sort of comprehensive Deep Knowing."
One of the most comprehensive protections at that time was called "V-Max!" which stood for Verify Maximum. What were called "nibblers" for disc copy software couldn't touch it even though those nibblers represented the ultimate in disk copy technology at the time. There were two ways to copy V-Max, the first was to get a dedicated hardware copying unit. The second was to apply a bit of knowledge with a debugger cartridge: the V-Max protection was a turn-key system you gave them files and they wrapped the protection around it and provided a fast-loader at the same time. So what you would do is fill all of memory (the whole 64K) with a value you knew say: $AF. Then you would load a V-Max file from the disc, it's loader would automatically take over and while it was loading you would enter your debugger cartridge and change it's exit point to point to itself. So instead of $0800: RTS you would make it $0800: JMP $0800. Then you would wait for the V-Max loader to fully load the file. Then a quick button press on your debugger cartridge and use the memory monitor to find where the file loaded by seeing what memory was NOT $AF. Then from the debugger cartridge save that memory block out again. Completely de-protected file. Since V-Max used standard kernel-load vectors the program itself needed no further modification, the protection was completely gone you just lost the fast-loader function. Which you then re-added yourself into a chunk of memory wherever the game didn't use it. Relocatable code was best for that. Later versions of V-Max also did on-the-fly decompression of files so occasionally while stripping the protection you would run into a situation where your destination disk ran out of space versus the original protected disk. Again, that was worked around by inserting your own custom loader into the kernel load-vectors which also did decompression. V-Max was impossible for copy software of the day to copy but with a little bit of knowledge and a debugger cartridge it was absolutely trivial to defeat.
Shh.
Should anyone wish to download an electronic copy (PDF) of Programming the Commodore 64 by R. C. West they may do so from DLH's Commodore Archive. It's a community supported archive of Commodore-related printed materials (books, magazines, newsletters, manuals etc.) and it could use your support. Enjoy.
There doesn't appear to be any section on custom high-speed communication with the external floppy drive unit. IIRC, you could upload a small program to the drive, and then you could in particular read data from the drive a lot faster than the 'OS' normally supported. This technique was also used to do copy protection for a bunch of titles, primarily by stepping the drive head 1/2 between tracks then doing reads. Production disk duplication could write to both the track & between tracks [or could write a wide enough track to cover the whole area], but regular floppy drives couldn't write both [you could either write on the track, or between tracks].
Not that I was interested in this stuff or anything.
Sleep your way to a whiter smile...date a dentist!
I was playing a game with some DRM (either StarForce or SecuROM) and it wouldn't run if I had a debugger present. I asked them why and they were all like "Anyone who has a debugger and is playing the game is a hacker." That's RIGHTLY earned state of paranoia.
And why did I spend time removing protection systems? Funny that part is: I owned an MSD floppy drive which was completely incompatible at a machine-language level with the 1541 drives everyone else owned and that all the game-makers wrote their protection systems for. So my floppy drive would load any of the software of the day. I literally bought a game, had to hack away the protection, and then I could play it on my computer. Of course no one will believe me when I say this but damnit, its the truth! Now get off my lawn.
Shh.
Octocore Core i13 and a half is just a fancy C64 with more CPU instructions, more memory, more peripherals that runs faster
Possible, but nowhere near as easy. I've read most of volume 3A of Intel's architecture reference while doing background reading for my Xen book, but the complete architecture reference is well over 3,000 pages. The GPU reference - if you can get it - is a similar length, and that's before you get to the OS. The Design and Implementation of the FreeBSD Operating System is 720 pages. It's a good book, but it skips over a lot of details. The copy of the X11 protocol reference that I read was several hundred pages, and it's a few revisions old. The OpenGL reference was a similar length. But now you can do 2D and 3D graphics and, once you've read the C spec (not so bad, only a couple of hundred pages) and spent some time familiarising yourself with your C compiler and standard library you can draw things.
To get the level of understanding that the original poster is talking about, on a modern computer, means reading and remembering around 10,000 pages of reference books, and gaining familiarity with the source code that they mention. And that's just going to give you one CPU architecture and the core bits of the OS.
I am TheRaven on Soylent News
Dude, back when I was a kid and had a C-64, I wrote a JVM for it. Unfortunately I had trouble, because while the JVM standard defines long as not being threadsafe (as a sop to 32-bit architectures), it defines operations on int, short, char, and Object references as being atomic. So I had to write single-threaded code to simulate multiple threads just to get the garbage collection to work. And my char mappings didn't support Arabic and Chinese- you had to stick with PETSCII.
I was so embarrassed in front of my friends when my games paused intermittently to clear out kilobytes of garbage from the little heap. They were like, WTF, what is it doing, and I said, give me a break, it's Java. The only program I ever really got to work right was my C-64 emulator.