SLR 1.1 Systems architecture

Question 1

What does ALU stand for?

Answer 1

Arithmetic Logic Unit

Question 2

What is the role of the ALU?

Answer 2

The Arithmetic Logic Unit (ALU) carries out arithmetic operations (maths) or logical comparisons. This allows a program to make decisions.

Question 3

What does CPU stand for?

Answer 3

Central Processing Unit

Question 4

What are registers?

Answer 4

“Tiny areas of extremely fast memory located in the CPU normally designed for a specific purpose, where data or instructions are stored temporarily.”

Question 5

What does PC stand for (in the context of the CPU)?

Answer 5

Program Counter

Question 6

What is the role of the PC?

Answer 6

“It is a register in the CPU which holds the address of the next instruction to be executed.”

Question 7

What does ACC stand for?

Answer 7

Accumulator

Question 8

What is the role of the ACC?

Answer 8

“Holds the results from the ALU (e.g. if a calculation like score = score + 100 or the result of a comparison like if lives == 0)”

Question 9

What does MAR stand for?

Answer 9

Memory Address Register

Question 10

What is the role of the MAR?

Answer 10

“It is a register in the CPU that stores the address in memory of the next instruction to be fetched, decoded and executed.”

Question 11

What does MDR stand for?

Answer 11

Memory Data Register

Question 12

What is the role of the MDR?

Answer 12

“It is a register in the CPU that stores data being transferred to or from memory.”

Question 13

What is an FDE cycle?

Answer 13

A Fetch, Decode and Execute cycle

Question 14

What happens during an FDE cycle?

Answer 14

“The complete process of retrieving an instruction from memory (RAM), decoding it and carrying it out. ”

Question 15

What does the CPU consist of?

Answer 15

“The CPU is the main part of the computer, consisting of the registers, ALU, cache, and control unit.”

Question 16

What is “clock speed”?

Answer 16

“The clock speed is the frequency at which the internal clock generates pulses. The higher the clock rate, the faster the computer will carry out the FDE cycle.”

Question 17

What are cores?

Answer 17

“Cores are the units responsible for the fetch-decode-execute cycle.”

Question 18

What is the cache?

Answer 18

Cache is extremely fast access memory within the CPU. Frequently used data and instructions are copied to the cache as it is quicker to access than RAM.

Question 19

What is Von Neumann Architecture?

Answer 19

A traditional computer architecture that forms the basis of most digital computer systems. A single control unit manages program control flow following a linear sequence of ‘fetch-decode-execute’ cycles.

Question 20

What is an embedded system?

Answer 20

An embedded system is a computer systems with a dedicated function within a larger mechanical or electrical system. For example washing machines, traffic lights, toasters and DVD players all have embedded systems - as do many, many other things!

Question 21

Name the main parts of a CPU

Answer 21

1. Arithmetic Logic Unit (ALU)
2. Control Unit (CU)
3. Cache
4. Registers

Question 22

Name the main registers a CPU has access to

Answer 22

1. Program Counter (PC)
2. Memory Address Register (MAR)
3. Memory Data Register (MDR)
4. Accumulator (ACC)

Question 23

What does the CU do?

Answer 23

Sends signals to control how data moves around the processor

Question 24

What are the units for clock speed?

Answer 24

Hertz (cycles per second - this shows how many instructions can be fetched, decoded and executed each second). Modern computers can do billions of FDE cycles per second so are rated in Giga Hertz