alt Hacker NewsNeat! I sometimes play around with the idea of reverse engineering and transcompiling a tiny game that I think was probably written in Turbo Pascal 4.0. Maybe 4.0 supported optimizations, but this program seems to have been compiled in a debug mode. (At least, it seems to have no optimization, and has the default {$S+} stack overflow checking at the start of every function.) The lack of optimization makes it (and perhaps other programs written in Turbo Pascal) a really attractive artifact to experiment with transcompiling. When I realized that only the first segment was the actual game, and the other three segments corresponded to standard units used for I/O (etc.), which could be harder to analyze, I realized I could just omit those segments and replace them with new functions suitable for the transcompilation target. Maybe some day I'll get around to finishing it.
Good luck!
Thank you!
It's similar with Turbo Pascal 3.0, but there's only one segment since it's a good old COM file. The compiler just copies its own first ~10000 bytes, comprising the standard library, and splices the compiled result to the end.
I can see how this makes transcompilation relatively straightforward, although the real mode 16-bit code is a bit unpleasant with all the segment stuff going on, so you might as well just decompile :D. It's very possible that similar instructions will be emitted in 3.0 and 4.0 for the same source input.
My program also has the stack checking calls everywhere before calling functions. I think that people using Pascal weren't worried about performance that much to begin with, so they didn't bother disabling it.