GCSE Computer
Science (OCR)
QUESTIONS AND
ANSWERS
Arithmetic Logic Unit (ALU) - ANSWER-Performs
operations on data e.g. Addition, subtraction
Control Unit (CU) - ANSWER-Coordinating activities
of the CPU
Registers - ANSWER-Quick, small stores of data
within the CPU
,Memory Address Register (MAR) - ANSWER-Holds
memory address for data or a instruction about to be
used by the CPU
Memory Data Register (MDR) - ANSWER-Holds
actual data or instruction
Accumulator - ANSWER-Stores results of
calculations in the ALU
Program Counter (PC) - ANSWER-Holds memory
address of the instruction for each cycle
Fetch - ANSWER-The next instruction is retrieved by
CPU from main memory
Decode - ANSWER-The instruction is broken down
and decided so computer can understand
Execute - ANSWER-The CPU performs what the
instructions told
Embedded System - ANSWER-A computer system
built within a large device e.g. Camera, washer, car
Volatile - ANSWER-Memory loses its data when
power of
, Non-volatile - ANSWER-Memory retains its data
when power is lost
Random Access Memory (RAM) - ANSWER-
Read/write - function is to load open programs and
operating system data currently in use - volatile
Read Only Memory (ROM) - ANSWER-Can only be
read, can't be changed, stores essential programs to
be run in order to boot the computer - non-volatile
Cache - ANSWER-A type memory that stores copies
of frequently used data, much faster than RAM,
lower capacity - closer to CPU
Buses - ANSWER-Collection of wires that carry
signals between various components of the
computer system
Central Processing Unit (CPU) - ANSWER-
Processes all of the data and instructions that make
the system work - can be effected by clock speed,
number of cores, cache size
Clock speed - ANSWER-How fast the computer
does the FDE cycle
Science (OCR)
QUESTIONS AND
ANSWERS
Arithmetic Logic Unit (ALU) - ANSWER-Performs
operations on data e.g. Addition, subtraction
Control Unit (CU) - ANSWER-Coordinating activities
of the CPU
Registers - ANSWER-Quick, small stores of data
within the CPU
,Memory Address Register (MAR) - ANSWER-Holds
memory address for data or a instruction about to be
used by the CPU
Memory Data Register (MDR) - ANSWER-Holds
actual data or instruction
Accumulator - ANSWER-Stores results of
calculations in the ALU
Program Counter (PC) - ANSWER-Holds memory
address of the instruction for each cycle
Fetch - ANSWER-The next instruction is retrieved by
CPU from main memory
Decode - ANSWER-The instruction is broken down
and decided so computer can understand
Execute - ANSWER-The CPU performs what the
instructions told
Embedded System - ANSWER-A computer system
built within a large device e.g. Camera, washer, car
Volatile - ANSWER-Memory loses its data when
power of
, Non-volatile - ANSWER-Memory retains its data
when power is lost
Random Access Memory (RAM) - ANSWER-
Read/write - function is to load open programs and
operating system data currently in use - volatile
Read Only Memory (ROM) - ANSWER-Can only be
read, can't be changed, stores essential programs to
be run in order to boot the computer - non-volatile
Cache - ANSWER-A type memory that stores copies
of frequently used data, much faster than RAM,
lower capacity - closer to CPU
Buses - ANSWER-Collection of wires that carry
signals between various components of the
computer system
Central Processing Unit (CPU) - ANSWER-
Processes all of the data and instructions that make
the system work - can be effected by clock speed,
number of cores, cache size
Clock speed - ANSWER-How fast the computer
does the FDE cycle
