Processor Fundamental

4.1 Central Processing Unit (CPU) Architecture

Candidates should be able to:

1. Show understanding of the basic Von Neumann model for a computer system and the stored program concept
2. Show understanding of the purpose and role of registers, including the difference between general purpose and special purpose registers

Notes and guidance

Special purpose registers including:

1. Program Counter (PC)
2. Memory Data Register (MDR)
3. Memory Address Register (MAR)
4. The Accumulator (ACC)
5. Index Register (IX)
6. Current Instruction Register (CIR)
7. Status Register

3. Show understanding of the purpose and roles of the Arithmetic and Logic Unit (ALU), Control Unit (CU) and system clock, Immediate Access Store (IAS)

4. Show understanding of how data are transferred between various components of the computer system using the address bus, data bus and control bus

5. Show understanding of how factors contribute to the performance of the computer system

Notes and guidance

Including:

• processor type and number of cores
• the bus width
• clock speed
• cache memory

6. Understand how different ports provide connection to peripheral devices

Notes and guidance

Including connection to:

• Universal Serial Bus (USB)
• High Definition Multimedia Interface (HDMI)
• Video Graphics Array (VGA)

7. Describe the stages of the Fetch-Execute (F-E) cycle

Notes and guidance

Describe and use ‘register transfer’ notation to describe the F-E cycle

8. Show understanding of the purpose of interrupts

Notes and guidance

Including:

1. possible causes of interrupts
2. applications of interrupts
3. use of an Interrupt Service handling Routine (ISR)
4. when interrupts are detected during the fetch-execute cycle
5. how interrupts are handled

4.2 Assembly Language

Candidates should be able to:

1. Show understanding of the relationship between assembly language and machine code

2. Describe the different stages of the assembly process for a two-pass assembler

Notes and guidance

Apply the two-pass assembler process to a given simple assembly language program

3. Trace a given simple assembly language program

4. Show understanding that a set of instructions are grouped

Notes and guidance

Including the following groups:

1. Data movement
2. Input and output of data
3. Arithmetic operations
4. Unconditional and conditional instructions
5. Compare instructions

10. Show understanding of and be able to use different modes of addressing

Notes and guidance

Including immediate, direct, indirect, indexed, relative

11. The following table is an example of an instruction set:

4.3 Bit manipulation

Candidates should be able to:

1. Show understanding of and perform binary shifts

Notes and guidance

Logical, arithmetic and cyclic Left shift, right shift

2. Show understanding of how bit manipulation can be used to monitor/control a device

Notes and guidance

Carry out bit manipulation operations test and set a bit (using bit masking)