I'd start here: The ASCII for '9' is 0b00111001, a UInt8 9 is 0b00001001 (this was of course deliberate). So (A & 0b11110000) << 4 + (B & 0b11110000) to get th

I'd start here: The ASCII for '9' is 0b00111001, a UInt8 9 is 0b00001001 (this was of course deliberate). So (A & 0b11110000) << 4 + (B & 0b11110000) to get the low byte, the high byte is an exercise for the reader, 16 bit jump table to the value, if there's a '-' you invert it.