3 major components of a CPU

• Arithmetic/Logic Unit (ALU)
• Control Unit (CU)
• Memory

Arithmetic/Logic Unit  (ALU)

Where data is held temporarily and where calculations take place

Control Unit  (CU)

• Controls and interprets the execution of insturctions
• Follows a sequence of actions that correspond to the fetch-execut instruction cycle
• Also contains the the program counter (PC) and the Memory Management Unit (MMU)

Memory

Where the instructions to execute and teh data are stored.

CPU Registers

• Single, permanent storage location within the CPU used for a defined purpose
• hold a binary value temporarily for storage, manipulation, and/or simple calculations

General Purpose registers

also known as accumulators; hold the data that are used for arithmetic operations as well as the results.

Program Counter

Holds address of current instruction being executed.

Instruction Register

Holds the actual instruction being executed.

Memory Address Register (MAR)

Holds the address of a memory location

Memory Data Register (MDR)

Holds a data value that is being stored to or retrieved from the location in the MAR.

Status Registers

Several 1-bit registers also known as FLAGS, used to keep track of special conditions such as arithmetic carry, overflow and error conditions.

What is the LMC formal instruction process for Subtract?

1. PC → Mar
2. MDR → IR
3. IR[addr] →MAR
4. A-MDR → A
5. PC+1 → PC

What is the LMC formal instruction process for Add?

1. PC → Mar
2. MDR → IR
3. IR[addr] →MAR
4. A+MDR → A
5. PC+1 → PC

What is the LMC formal instruction process for Input?

1. PC → Mar
2. MDR → IR
3. Inbox → A
4. PC+1 → PC

What is the LMC formal instruction process for Output?

1. PC → Mar
2. MDR → IR
3. A → Outbox
4. PC+1 → PC

What is the LMC formal instruction process for Halt?

1. PC → Mar
2. MDR → IR

What is the LMC formal instruction process for Branch?

1. PC → Mar
2. MDR → IR
3. IR[addr] → PC

What is the LMC formal instruction process for Branch Zero?

1. PC → Mar
2. MDR → IR
3. IF A ==0:IR[addr] → PC
4. ELSE:PC+1 → PC

What is the LMC formal instruction process for Branch Positive?

1. PC → Mar
2. MDR → IR
3. IF A=>0:IR[addr] → PC
4. ELSE:PC+1 → PC

What is the LMC formal instruction process for STORE?

1. PC → Mar
2. MDR → IR
3. IR[addr] → MAR
4. A → MDR
5. PC+1 → PC

What is the Formal LMC instruction process for Load?

1. PC → Mar
2. MDR → IR
3. IR[addr] → MAR
4. MDR → A
5. PC+1 → PC

What is the LMC formal instruction process for CALL (PUSH)?

1. PC → Mar
2. MDR → IR
3. PC+1 → STACK
4. IR[addr] → PC

What is the formal LMC instruction process for RETURN (POP)?

1. PC → Mar
2. MDR → IR
3. STACK → PC

Define a Bus:

A group of electrical conductors suitable for carrying conputer signals fro one location to another.

List three Bus types:

1. Point-to-Point: Carries signals from one source to one destination
2. Multi-Point:  Connects several points together
3. System:  Connects teh CPU with memory and/or I/O module cards.

What is the purpose of an interface bridge?

To connect different buses

What is explicit addressing?

The source and destination are stated as part of the command

What is implicit addressing?

The source or destination is not specified as an argument but is part of the op codes

What are priviliged instructions?

Instructions reserved for use by the OS only

What are Non-Priviliged instructions?

Instructions that can be used by any program

What are Move instructions?

• Some of the most common instructions
• includes load, store and memory movement
• arguments can range in size from single bytes to many bytes

What are arithmetic instructions?

Basic functions for adding and subtracting, multiplying and dividing

What are Boolean Logic instructions?

Instructions for AND-ing, OR-ing, XOR-ing and NOT-ing arguments.

What are Single Operand manipulation instructions?

• Small and use only one argument
• example would be incrementing (INC) and decrementing (DEC) registers and memory

What are Bit Manipulation instructions?

Allows the setting or clearing of individual bits in bytes, words, or registers.

What are Shift and Rotate instructions?

• Shift:  Moves the data bits left or right one or more bits.
• Rotate:  Rotates the data bits left or right one or more bits, and the bit that is shifted out of the end is placed into the vacated space at the other end.

What do Program Control instructions do?

Change the flow of a program.

What will the Call and Return instructions do?

Allows the program to branch to subroutines and Return to the next instruction after the Call was made.

What is a Stack?

• Used to store data when the most recently used data is the first needed.
• Referred to as LIFO (last in first out)

What are Push and Pop used for?

to add and  and remove values to/from a stack

What is a Multiple Data Instruction?

• Provides a way of performing the same operation to multiple pieces of data
• Usually reserverd for special case processiong, i.e. graphics and 3D

How many licks does it take to get to the center of a

Tootsie Roll Pop?

Try it and see for yourself...

What is an interface bridge?

Used to connect different busses