--- Command 0xC7 Handler (0xE08F7C) ---
0xE08F88: MOVX @DPTR, A     ; Write to external register
0xE08F8B: MOVX A, @DPTR     ; Read from external register  
0xE08F8C: RETI              ; Return from interrupt

--- Command 0x81 Handler (0xE08EA7) ---
0xE08EC7: LCALL 0x9054      ; Call subroutine (external region)
0xE08EEE: RETI              ; Return from interrupt

--- Buffer Writes ---
0xE08230: MOVX @R1, A
0xE08BE4: MOVX @R1, A  
0xE08C1A: MOVX @R0, A