Download Processor Instruction Set

Processor Instructions set.
Learning Objectives
• Learn how to use mnemonics to write code using
assembly language.
• Learn the difference between immediate and direct
addressing
• Learn how to use different types of operation codes:
Data transfer, arithmetic operation, logical bitwise
operations and branch operations.
Processor Instruction Set
Instruction set
Different types of instruction set with different mnemonics
1. CISC (Complex instruction set)
2. RISC (Reduced instruction set)
cmp
r1, #10
Compare the value in register 1 with the value 10
cmp
R1,
#10
OPCODE
OPERAND
OPERAND
# = Addressing
Mode
Processor Instruction Set
Instruction set
OPCODE
• Mnemonic – style and type determined by the instruction set
• Example: CMP, ADD, MOV, LDA
• Bits are allocated for opcode, operand and addressing mode
• Example – 32 Bit (12 – opcode / 4 – Addressing mode / 16 –
Operand)
Processor Instruction Set
Addressing
Direct addressing
This is whereby a memory address is provided where the data
can be obtained.
LDR r1, 100
‘load data stored in address 100 into the
register
Immediate Addresssing.
This is whereby an actual value is provided rather than a
memory address
MOV r1, #10
‘move the value 10 into the register
Processor Instruction Set
Operation codes
• Data transfer operations
• Moves data between registers and main memory
• MOV, STR,LDR (Move, Store, Load)
• Arithmetic operations
• Opcodes that do basic arithmetic such as subtract, Add,
increment, decrement, negate, compare and shift
• ADD, SUB, CMP, LSL, LSR etc..
• Logical Operations
• Performs the logical operations – AND, OR, NOT, XOR
• Each bit of the data is compared during the operation
• Used to compare values and calculate them.
• AND, ORR, EOR, MVN
Processor Instruction Set
Operation codes
• Branch Operations
• Allows a program to branch to another memory address –
thereby a different part of the program after evaluating a
condition. Or they can branch unconditionally.
•
•
•
•
•
B – Branch always
BNE – Branch if not Equal
BEQ – Branch if equal
BGT – Branch if greater than
BLT – Branch if less than
A label then follows the opcode
BGT Alabel
Processor Instruction Set
Task
Use the LMC to write a division program that takes in two
numbers and outputs both the answer and the remainder.