1. RESET — clear the CPU and panel
2. ADRS SET, then four hex digits — point at an address
3. two hex digits, then WRITE INCR — store a byte and advance to the next address
4. READ INCR / READ DECR — step to the next or previous address
5. MODE — AUTO makes RUN free-run to HLT; STEP makes RUN execute one instruction (showing PC/A/flags) and RET keep stepping
6. STORE DATA / LOAD DATA — save or restore the [address, data] memory range via the browser's local storage, standing in for the real machine's cassette interface. Plays the actual cassette-interface tone (ch. 6 of the manual: a few-kHz carrier, on/off-keyed bit by bit at 110 baud) for the transferred bytes
7. load @ — load a program directly into memory at an address (or pick a sample program from the dropdown)

The real TK-80's monitor ROM is NEC's copyrighted firmware and isn't included here — this panel's address/write/run logic is reimplemented directly instead of running that ROM.