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hello_chr.oph | ||
hello_ines.oph | ||
hello_prg.oph | ||
hello_unif.oph | ||
README.txt |
This is a "Hello World" program for the Nintendo Entertainment System, which uses the sprite system to display and color-cycle the letters. Since NES cartridges tended to have sophisticated circuitry built into them that controlled memory addressing, several standards have arisen to represent this information. The program code for "Hello, NES" is split into two halves; a hello_prg.oph containing the executable code (PRG-ROM), and a hello_chr.oph containing the graphics tile information (CHR-ROM). These can then be packaged one of two ways - the popular iNES format (hello_ines.oph) or the mostly-defunct UNIF format (hello_unif.oph). Simply running ophis hello_ines.oph or ophis hello_unif.oph should produce hello.nes and hello.unf, respectively. Although UNIF is not a common format, its "chunk" system is not rare. The hello_unif.oph file demonstrates some techniques for automatically computing chunk sizes in Ophis. Be warned that as these techniques use the program counter, attempting to use labels to compute chunk size of assembled code is likely to backfire spectacularly - this technique should really only be used for inline strings and data.