The ROM has 4 'words' of 4 bits each. Only 5 components per word, 4 resistors for the output lines, and 4 gates for address decoding. I'd say "I'm getting better at this" but for the spectacular mistake I'm not telling you about. :)
Diodes face left (towards common connection) for 0, or right for 1. You could omit the 0 diodes, I guess.
