该指令系统包含三地址指令、双地址指令、单地址指令和零地址指令

指令长度为16位，包括4位基本操作码字段和三个4位地址字段

根据给定的各类指令的条数，设计出合理的扩展操作码方案-The instruction system includes a three-address instruction, two-address instruction, single-address instruction and zero-address instruction length of 16 instructions, including the four basic operations and three 4-bit code field address field according to the given instructions of various types of the number of design and reasonable extension of the program opcode