Octal vs Hex representations of machine code (was Re: TTL HEX LED driver chip)

On 10/27/10, Tony Duell <ard at p850ug1.demon.co.uk> wrote: Agreed. When I first started working with PDP-11s, my supervisor asked me for a PDP-11 program that would read the "window" register on our product then write it back to the same address and loop (it was a write-only register for each side - what each processor read was what the other had previously written). I thought a second and recited, "1000 slash 13700 lf 177300 lf 10037 lf 177300 lf 137 lf 1000 enter 1000 G" (or something substantially similar to that). He got annoyed and told me to go sit down and write him a program. I told him to turn around and type in what I was telling him. On the third recitation, he started typing. Being two moves and a jump, it worked the first time. He was gobsmacked that it was possible for a human to spontaneously emit meaningful octal. Given the spacing of the addressing modes, I wouldn't have wanted to try it in hex without writing it down. -ethan