COMPUTER SCIENCE EXAM STUDY GUIDE
1. List two components with which the CPU works to execute program instructions. ANS
Memory
Input and Output Devices
2. Describe the role of the Control Unit in the fetch-decode-execute cycle. ANS The
control unit coordinates the actions of the computer. It sends out control signals to other
parts of the CPU and to other components of the computer.
3. State the function of the Program Counter. ANS This holds the address of the next
instruction to be fetched.
4. State the function of the Memory Data Register (MDR). ANS The MDR is temporary
store(buffer) for anything copied from memory.
5. State the function of the Accumulator. ANS The accumulator is a temporary store for
the results of calculations carried out by the ALU.
6. State two components of Von Neumann's design in addition to the CPU. ANS Memory
to store program data and instructions.
Input and output devices.
, COMPUTER SCIENCE EXAM STUDY GUIDE
7. Define the term "stored program concept" ANS A computer in which the program
instructions and the data are stored in memory.
8. State the role of RAM in the fetch-decode-execute cycle. ANS RAM is where the
program instructions and data are stored until they are needed.
9. Describe what is meant by a register. ANS A register is a memory location within the
CPU used to store program instructions and/or data.
10. Explain why cache memory is used in the CPU. ANS The cache consists of very fast
memory and it is used to store frequently used commands and data. These can be
accessed more quickly from the cache than from the slower RAM when they are
needed.
11. The performance of a CPU can be improved by increasing its clock speed. Explain why
performance cannot be increased indefinitely by increasing the
clock speed. ANS Performance cannot be improved indefinitely because the rate at which
the transistors process the instructions is limited.
There can also be a problem with the amount of heat generated by high clock speeds,
which may cause a malfunction if it cannot be dissipated.
12. Give one reason why cache memory is not used for RAM. ANS Too expensive.
, COMPUTER SCIENCE EXAM STUDY GUIDE
13. Define what is meant by an 'embedded system'. ANS An embedded system is a
computer system built into another device in order to control it.
14. Identify three components of an embedded system. ANS Processor Memory
Input and output interfaces.
15. Explain the difference between 'general purpose machines' and 'embedded
systems'. ANS Desktop computers are designed to run a range of different applications
e.g. word processors, spreadsheets etc. while each embedded system is designed to
perform a small, specific range of functions linked to the device it is embedded into.
16. Explain why low-level languages such as assembly language are used for writing the
programs for embedded systems. ANS Assembly language is used so that the hardware
can be directly controlled by the programs written. This is far more efficient than using
a high-level language that needs an interpreter or compiler.
17. Define what is meant by 'volatile memory'. ANS Volatile memory provides
temporary storage for program instructions and data. It loses its content when the
power is switched off.
1. List two components with which the CPU works to execute program instructions. ANS
Memory
Input and Output Devices
2. Describe the role of the Control Unit in the fetch-decode-execute cycle. ANS The
control unit coordinates the actions of the computer. It sends out control signals to other
parts of the CPU and to other components of the computer.
3. State the function of the Program Counter. ANS This holds the address of the next
instruction to be fetched.
4. State the function of the Memory Data Register (MDR). ANS The MDR is temporary
store(buffer) for anything copied from memory.
5. State the function of the Accumulator. ANS The accumulator is a temporary store for
the results of calculations carried out by the ALU.
6. State two components of Von Neumann's design in addition to the CPU. ANS Memory
to store program data and instructions.
Input and output devices.
, COMPUTER SCIENCE EXAM STUDY GUIDE
7. Define the term "stored program concept" ANS A computer in which the program
instructions and the data are stored in memory.
8. State the role of RAM in the fetch-decode-execute cycle. ANS RAM is where the
program instructions and data are stored until they are needed.
9. Describe what is meant by a register. ANS A register is a memory location within the
CPU used to store program instructions and/or data.
10. Explain why cache memory is used in the CPU. ANS The cache consists of very fast
memory and it is used to store frequently used commands and data. These can be
accessed more quickly from the cache than from the slower RAM when they are
needed.
11. The performance of a CPU can be improved by increasing its clock speed. Explain why
performance cannot be increased indefinitely by increasing the
clock speed. ANS Performance cannot be improved indefinitely because the rate at which
the transistors process the instructions is limited.
There can also be a problem with the amount of heat generated by high clock speeds,
which may cause a malfunction if it cannot be dissipated.
12. Give one reason why cache memory is not used for RAM. ANS Too expensive.
, COMPUTER SCIENCE EXAM STUDY GUIDE
13. Define what is meant by an 'embedded system'. ANS An embedded system is a
computer system built into another device in order to control it.
14. Identify three components of an embedded system. ANS Processor Memory
Input and output interfaces.
15. Explain the difference between 'general purpose machines' and 'embedded
systems'. ANS Desktop computers are designed to run a range of different applications
e.g. word processors, spreadsheets etc. while each embedded system is designed to
perform a small, specific range of functions linked to the device it is embedded into.
16. Explain why low-level languages such as assembly language are used for writing the
programs for embedded systems. ANS Assembly language is used so that the hardware
can be directly controlled by the programs written. This is far more efficient than using
a high-level language that needs an interpreter or compiler.
17. Define what is meant by 'volatile memory'. ANS Volatile memory provides
temporary storage for program instructions and data. It loses its content when the
power is switched off.
