Three byte instruction
The instruction which have 16 bit data address as its operand are three byte instruction. They need three memory locations to store them in memory.
Followings are some examples of three byte instructions .
LXI 16 bit
JMP 16 bit address
CALL 16 bit address
Let us consider a jump instruction JMP 2050H. Now notice how this instruction is stored in the memory.
Notice that first byte is the operation code. Second byte is the low order byte of the 16 bit data address. Third byte is the high order byte of the 16 bit data address.
Note :Low order byte of 16 bit address is multiplexed with data bus and requires de multiplexing which requires additional time. But high order byte of the address does not require de multiplexing therefore we write low order byte first. The de multiplexing is already discussed in cahpter2.