My first assignment at my first professional programming job (way back in 1980) was to write a 6502 macro assembler that ran on an Ohio Scientific machine. We took those machines and built our own OS and a three-user travel agency automation package that worked remarkably well, given the constraints of 48K of RAM and 2 floppy disks.
I did some research in to hashing, simulated a couple of hashing functions in FORTRAN (I was still in school), and found a good way to optimize the function to avoid collisions on the core set of 6502 opcodes. This earned me an immediate raise from $7/hour to $9/hour.
The assembler ran blazingly fast and I still have the listings for it. As soon as it was able to self-assemble, I added macros for all of the opcodes that rightfully belonged in the 6502 ISA but were not there. Mostly a set of loads and transfers that made the ISA almost fully orthogonal.
I did some research in to hashing, simulated a couple of hashing functions in FORTRAN (I was still in school), and found a good way to optimize the function to avoid collisions on the core set of 6502 opcodes. This earned me an immediate raise from $7/hour to $9/hour.
The assembler ran blazingly fast and I still have the listings for it. As soon as it was able to self-assemble, I added macros for all of the opcodes that rightfully belonged in the 6502 ISA but were not there. Mostly a set of loads and transfers that made the ISA almost fully orthogonal.