1.1.1 Structure and Function of the Processor Key Terms

Question 1

ALU

Answer 1

Arithmetic Logic Unit - the part of the CPU where data is processed and manipulated using arithmetic and logical operations

Question 2

Control Unit

Answer 2

The part of the CPU that manages the FDE Cycle by signalling other parts of the processor and RAM

Question 3

Decode Unit

Answer 3

The part of the CPU that interprets instructions

Question 4

Register

Answer 4

Small areas of extremely fast memory located in the CPU designed for a specific purpose, where data or control information is stored temporarily

Question 5

PC

Answer 5

Program Counter - Stores the address of next instruction to be fetched. Incremented every cycle but can be changed by branch commands

Question 6

ACC

Answer 6

Accumulator - Used to hold data currently being processed. Stores user input, output from ALU and data retrieved from RAM.

Question 7

MAR

Answer 7

Memory Address Register - Stores the address of the memory location to be accessed / currently being accessed. Loads Address onto the Address Bus

Question 8

MDR

Answer 8

Memory Data Register - stores the information (data and instructions) retrieved from RAM, or output to RAM from ACC. Loads data onto and receives data from the Data Bus.

Question 9

CIR

Answer 9

Current Instruction Register - stores the instruction currently being executed and decoded.

Question 10

Busses

Answer 10

A physical path (set of wires) used to send signals between components.

Question 11

Data Bus

Answer 11

Connection between the MDR and RAM, used to transmit data and instructions. Transmits data in both directions.

Question 12

Address Bus

Answer 12

Connection between the MAR and RAM, used to transmit addresses. Transmits data in only one direction - MAR to RAM.

Question 13

Control Bus

Answer 13

Connection between the Control Unit and RAM, used to transmit control signals such as read, write and ready instructions. Transmits data in both directions

Question 14

FDE

Answer 14

Fetch - Decode - Execute. The Cycle by which the CPU retrieves instructions from RAM, decodes what the instruction is and then carries out those instructions.

Question 15

CPU

Answer 15

Central Processing Unit - The main component of a computer, contains registers and units which execute instructions.

Question 16

Clock

Answer 16

A device internal to the CPU which sends regularly timed pulses to the Control Unit, in order to manage the FDE Cycle.

Question 17

Clock Speed

Answer 17

Measured in Hertz (Hz), pulses per second. Higher Clock speeds mean more instructions executed per second. Modern Processor speeds and measured in Gigahertz (GHz).

Question 18

Cores

Answer 18

Discrete CPUs held on a single Processor Chip, which can operate by executing instructions in parallel to speed up processing of data.

Question 19

Cache

Answer 19

A section of memory held within or very close to the CPU, used to store regularly used or soon to be accessed instructions. Very fast access speeds compared to RAM. More Cache means faster processing speeds.

Question 20

Pipelining

Answer 20

Carrying out the steps of the FDE Cycle concurrently. As one instruction is being decoded, the previous instruction is being executed and the next instruction is being fetched. Branching causes the pipeline to be flushed.

Question 21

Von Neumann Architecture

Answer 21

Single Control Unit manages FDE Cycle. Single set of Buses between CPU and RAM. Data and Instructions are stored in the same location and same format.

Question 22

Harvard Architecture

Answer 22

Single Control Unit Manages the FDE Cycle. Two sets of buses used for carrying data and instructions. Data and Instructions stored in separate areas of Memory and in different formats.

Question 23

Contemporary Architecture

Answer 23

Any modern set of disciplines that describes the functionality, the organisation and the implementation of computer systems.