6502.txt twos complement
Various places in the 6502.txt document that refer to negative numbers don't seem to realize that it's 6502 uses twos complement - not just a simple sign bit. This is semantically important, for example in the section about branch instructions it states that they have a range of 127 forward and backward - this is inaccurate, twos complement represents 128 values backwards (which is its advantage over a simple sign bit representation, which loses a bit by representing +0 and -0).
PAL frequency formula
15625 Hz * 283.75 + 25 Hz = 4433618.75 Hz