Decoding the Mystery of The Wizard's Castle BASIC Comment
10 REM"_(C2SLFF4
I investigated a strange comment in the 1980s Exidy Sorcerer game The Wizard's Castle that looked like garbage but was actually hidden machine code. With help from Josh and Chris, we discovered this REM statement executes Z80 assembly to seed the random number generator by manipulating screen memory. This clever trick allowed the game to generate unique dungeons without user input.
It is literally calling the text of the REM statement as Z80 machine code!
- nneonneo
Hmm, based on the (handwritten!) notes on Table F-2 in http://bitsavers.informatik.uni-stuttgart.de/pdf/exidy/DP500..., it looks like pressing Graphic+key would allow you to enter BASIC tokens from 0x80 to 0xBF, while pressing Graphic+Shift+key would allow you to access 0xC0 to 0xC6. By inference, it seems like Graphic+Shift+key should allow access to the entire 0xC0 to 0xFF space, but most of those keys are undocumented.
Based on this, I wonder if it's worth trying the following:
10 REM [Graphic+Shift+=] [_] [(] [Graphic+Shift+NumpadPlus] [2] [Graphic+Shift+NumpadEquals] [Graphic+Shift+Numpad6] [Graphic+Shift+0]
Note that you'll probably need an emulator with accurate keyboard emulation - or a real device - in order to type these in. However, with the emulator from http://www.liaquay.co.uk/sorcerer, I was able to confirm that Graphic+Shift+0 produced 201 (rendered as F4), and Graphic+Shift+= produced 255 (rendered as S), so I think this approach will work.
- RiverCrochet
> Would this work on other platforms, I wonder? Or would they just freak out? Someone else can give it a try on the Commodore 64 or something.
I don't remember seeing this on Commodore 64 too much. Most type-in hybrid BASIC-machine language programs would have numerous DATA statements with opcodes and a loop to READ and POKE them (typically in the tape buffer area somewhere in the fist 2K of RAM or in the 4K area at 49152/$C000).
Commodore 64 BASIC's LOAD"WHATEVER",8 command would load a file of any size in the BASIC text area without validation or checking it for any type of format. So much commercial C64 software often had a one line "10 SYS2063" (or similar) stub that would simply jump into the actual code which was tacked on to that BASIC stub. But the LIST command wouldn't display anything after the stub - I guess the "next line" bytes were set to $0000 to indicate end of program.
- sedatk
That's why some computer mags started introducing tools to type in programs without ambiguities.
Here's a recent example I made: an Amstrad CPC program that's both valid BASIC and machine code at the same time, and running it both ways (RUN or CALL &170 -- loading address of the BASIC program) produce the same output: https://github.com/ssg/yello
- JSR_FDED
See this is why I never understood LISP people proudly proclaiming that “code is data and data is code”… we were doing this in BASIC for decades already!
- NetMageSCW
This makes me sad about the history that has been forgotten. I never used a Sorcerer but I knew what the code was for at a glance.