2: CPU

Question 1

5 tasks by processor

Answer 1

1. Fetch instruction - read from memory
2. Integrate instruction - decode to determine action
3. Fetch data
4. process data
5. Write data - to memory or I/O module

Question 2

3 types of system bus

Answer 2

• control bus
• data bus
• address bus

Question 3

4 steps of machine cycle

Answer 3

1. fetch (CU)
2. decode (CU)
3. execute (ALU)
4. store (ALU)

• CU direct and coordinate operation
• ALU perform execution

Question 4

3 operations and examples carries out in ALU

Answer 4

1. arithmetic: calculation - 加减乘除
2. comparison: comparing data items - greater/less than
3. logical: conditions and logical operators - OR/AND/NOT

Question 5

define I time

Answer 5

Instruction time
- time taken to fetch data and instructions from memory and store in internal register

Question 6

define E time

Answer 6

Execution time
- time taken to decode and execute the instructions

Question 7

pipelining

Answer 7

• multiple instructions are overlapped in execution
• execute more instructions in smaller period of time
• laundry analogy

Question 8

3 classifications of microprocessor

Answer 8

• design of semiconductor technologies
• width of data format
• instruction set

Question 9

3 design of semiconductor technologies

Answer 9

• TTL (Transistor-Transistor Logic)
• CMOS (Complementary-Metal-Oxide-Semiconductor)
• ECL (Emitter-Coupled Logic)

Question 10

Characteristics of 3 design of semiconductor

Answer 10

TTL - most commonly used

CMOS
- low power consumption
- suitable for portable computer and battery-powered devices

ECL
- high power consumption
- high speed

Question 11

CISC and RISC

Answer 11

Complex-Instruction-Set computer
- easier to program
- slower
- more expensive