- emulators/simulators/FPGA code

- books, data sheets, OCR'd PDFs of books and data sheets, text files copy/pasted from PDFs or retyped from books and data sheets

Code is likely to be heavily tested, but it makes extracting high-level information about the instruction set very difficult.

Data is easy to analyse and synthesise, but since it's described in prose there's no easy way to test or validate it - if somebody in 1984 made a typo that a particular instruction took 3 cycles instead of 2, and that error was copy/pasted and made its way into half the "6502 instruction set" websites online, how would you know? How would you detect it?

Using SQL to enforce constraints and validation gives me confidence that there aren't a bunch of typos and copy/paste errors in this data. In addition, being able to express special cases like "read-modify-write instructions applying to the accumulator do not pay the three cycle penalty" in code rather than in prose makes it more likely they will be applied correctly. Lastly, since the result is an SQL database, it can be pretty easily formatted to resemble any book or data sheet you like for simplified visual verification against book/data sheet sources.

https://lite.datasette.io/?sql=https://gist.github.com/simon...