Intel mcs-48 manual Instruction SET

INSTRUCTION SET

4.0 INTRODUCTION

The. MCS-48 instruction set is extensive for a machine of its size and has been tailored to be straightforward and very efficient in its use of program memory. All instructions are either one or two bytes in length and over 70% are only one byte long. Also, all instructions execute in either one or two cycles (2.5J.Lsec or 5.0J.Lsec when using a 6 MHz XTAL) and over 50% of all instructions execute in a single cycle. Double cycle instructions include all immediate instruc- tions, and all I/O instructions.

The MCS-48 microcomputers have been designed to efficiently handle arithmetic operations in both binary and BCD as well as to efficiently handle the single bit operations required in control applications. Special instructions have also been in- cluded to simplify loop counters, table lookup routines, and N-way branch rou- tines.

Data Transfers

As can be seen in the accompanying diagram, the 8-bit accumulator is the central

i ----------- l

EXPANDER

I/O PORTS 4-7

I

I

I

I

,W_---=:..:,:,::-=--J.....J

PROGRAM		DATA	I
MEMORY		MEMORY	I
(!tdata)	MOV
ADD			I
MOV			I
MOVP
MOVP3

EXTERNAL

MEMORY

AND

PERIPHERALS

ANL	8048
ORL
	8049	I
	8748
	8035*	*NO PROGRAM

8039* I MEMORY

~________ ---.J

DATA TRANSFER INSTRUCTIONS

4-1