H is a hexadecimal symbol, the data after H is the hexadecimal data of data, and ORG is a pseudo-instruction to locate the address at compile time, which means that the instruction after the statement is executed from the address after ORG. Different single-chip computers have different starting addresses. For example, 5 1 starts from 0000H, so the first sentence of 5 1 single chip microcomputer is ORG 0000H.