A level Computer Science Key Terms (OCR - H446)
1. ALU: Arithmetic Logic Unit
"The part of the CPU where data is processed and manipulated. This processing and
manipulation normally consists of arithmetic operations or logical comparisons
allowing a program to make decisions."
2. CU: "The part of the CPU that manages the execution of instructions. The control unit
fetches each instruction
In sequence, and decodes and synchronises it before executing it by sending control
signals to other parts of the computer."
3. Register: "Tiny areas of extremely fast memory located in the CPU normally
designed for a specific purpose,
Where data or control information is stored temporarily."
4. PC: Program Counter
"A register in the control unit which holds the address of the next instruction to be
executed."
5. ACC: Accumulator
A special register within the ALU. It is used to hold the data currently being processed by
the central processor. Any data to be processed is stored temporarily in the accumulator,
the results ending up back in the accumulator being stored in the memory unit."
6. MAR: Memory Address Register
,"A register in the CPU that stores the address of the memory location currently in use. In
the fetch phase, this would be the address of the instruction being loaded; in the execute
phase, it would be the address of the data being used."
7. MDR: Memory Data Register
"A register in the CPU that stores data being transferred to and from the immediate-
access store. It acts as a butter, allowing the central processor and memory unit to act
independently without being attected by minor ditterences in operation. A data item will
be copied to the MDR ready for use at the next clock pulse, when it can either be used
by the central processor or be stored in main memory."
8. CIR: Current Instruction Register
"A register in the control unit that stores the address of the next instruction currently being
executed and decoded."
9. Buses: "A common physical pathway shared by signals to and from several
components of a computer."
10. Data Bus: "A common physical pathway shared by signals to and from several
components of a computer."
11. Address Bus: "The part of the bus which carries identification about where the
data is being sent."
Control Bus: "This bus carries command and control signals to and from
12.
every other component of a computer."
,13.Fetch-Decode-Execute: "The complete process of retrieving an instruction
from store, decoding it and carrying it out. Also known as the instruction cycle."
, 14. CPU: Central Processing Unit
"The main part of the computer, consisting of the registers, ALU and control unit."
15.Clock Speed: "Measured in Hertz, the clock speed is the frequency at which
the internal clock generates pulses. The higher the clock rate, the faster the computer
may work. The "clock" is the electronic unit that synchronises related components by
generating pulses at a constant rate."
16. Cores: "A part of a multi-core processor. A multi-core processor is a single
component with two or more
Independent actual cpus, which are the units responsibly for the fetch-decode-execute
cycle."
17.Cache: "A part of the main store between the central processor and the rest of the
memory. It has extremely fast access, so sections of a program and its associated data
are copied there to take advantage of its short fetch cycle."
18.Pipelinning: "The concurrent decoding of two or more machine instructions. While
part of one instruction (for example, an address field) is being decoded, another part of
a second instructions (for example, an operation code) may also be decoded."
19. Von Neumann Architecture: "Traditional computer architecture that forms
the basis of most digital
Computer systems. A single control unit manages program control flow following a linea
1. ALU: Arithmetic Logic Unit
"The part of the CPU where data is processed and manipulated. This processing and
manipulation normally consists of arithmetic operations or logical comparisons
allowing a program to make decisions."
2. CU: "The part of the CPU that manages the execution of instructions. The control unit
fetches each instruction
In sequence, and decodes and synchronises it before executing it by sending control
signals to other parts of the computer."
3. Register: "Tiny areas of extremely fast memory located in the CPU normally
designed for a specific purpose,
Where data or control information is stored temporarily."
4. PC: Program Counter
"A register in the control unit which holds the address of the next instruction to be
executed."
5. ACC: Accumulator
A special register within the ALU. It is used to hold the data currently being processed by
the central processor. Any data to be processed is stored temporarily in the accumulator,
the results ending up back in the accumulator being stored in the memory unit."
6. MAR: Memory Address Register
,"A register in the CPU that stores the address of the memory location currently in use. In
the fetch phase, this would be the address of the instruction being loaded; in the execute
phase, it would be the address of the data being used."
7. MDR: Memory Data Register
"A register in the CPU that stores data being transferred to and from the immediate-
access store. It acts as a butter, allowing the central processor and memory unit to act
independently without being attected by minor ditterences in operation. A data item will
be copied to the MDR ready for use at the next clock pulse, when it can either be used
by the central processor or be stored in main memory."
8. CIR: Current Instruction Register
"A register in the control unit that stores the address of the next instruction currently being
executed and decoded."
9. Buses: "A common physical pathway shared by signals to and from several
components of a computer."
10. Data Bus: "A common physical pathway shared by signals to and from several
components of a computer."
11. Address Bus: "The part of the bus which carries identification about where the
data is being sent."
Control Bus: "This bus carries command and control signals to and from
12.
every other component of a computer."
,13.Fetch-Decode-Execute: "The complete process of retrieving an instruction
from store, decoding it and carrying it out. Also known as the instruction cycle."
, 14. CPU: Central Processing Unit
"The main part of the computer, consisting of the registers, ALU and control unit."
15.Clock Speed: "Measured in Hertz, the clock speed is the frequency at which
the internal clock generates pulses. The higher the clock rate, the faster the computer
may work. The "clock" is the electronic unit that synchronises related components by
generating pulses at a constant rate."
16. Cores: "A part of a multi-core processor. A multi-core processor is a single
component with two or more
Independent actual cpus, which are the units responsibly for the fetch-decode-execute
cycle."
17.Cache: "A part of the main store between the central processor and the rest of the
memory. It has extremely fast access, so sections of a program and its associated data
are copied there to take advantage of its short fetch cycle."
18.Pipelinning: "The concurrent decoding of two or more machine instructions. While
part of one instruction (for example, an address field) is being decoded, another part of
a second instructions (for example, an operation code) may also be decoded."
19. Von Neumann Architecture: "Traditional computer architecture that forms
the basis of most digital
Computer systems. A single control unit manages program control flow following a linea
