You need to encode the message in ASCII format (20 letters: 0H-13H) . Caution: UART_TX buffer size is only 16 bytes!! cold_start: load s0, s0; I/NOP Load sO, ascii_W Store s0, 00 Load so, asci E Store s0, 01 Load s0, ascii_k Store s0, 12 Store s0, 13 /Scratch pad memory adfresses are in HEX