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Computer science -paper 1
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Protocols
Computer science -paper 1
22 cards
Cards (41)
The CPU is the
central processing unit
, it carries out program
instructions
using data
Components inside the CPU
ALU (Arithmetic Logic Unit)
Control Unit
Cache
Registers
ALU
Carries out maths and logic needed to execute instructions
Control
Unit
Coordinates the
fetch-execute
cycle and
decodes
instructions
Cache
Small, fast memory that holds frequently accessed items
Special
purpose registers
Memory Address Register
(MAR)
Memory Data Register
(MDR)
Program Counter
Accumulator
Fetch-Execute Cycle
1. Fetch instruction from memory using Program Counter
2. Decode instruction
3. Execute instruction, possibly fetching data
Clock speed
Rate
at which the fetch-execute cycle is carried out, in
GHz
CPU
performance factors
Clock speed
Number of cores
Cache size
Embedded systems
Computers built into other devices, with one specific purpose
Types
of storage
Primary
(RAM, ROM)
Secondary
(HDD, SSD, optical)
RAM
Volatile memory, contents lost when power is off
ROM
Non-volatile memory, contains startup program
Secondary storage types
Hard disk drives: reliable, large capacity, fragile
Optical discs: portable, reliable, fragile
Solid state drives: fast, durable, expensive
Binary
units
Bit
Nibble
Byte
Kilobyte
Megabyte
Gigabyte
Binary addition
1. Carry 1 to next column for 1+1
2. Carry 1 for 1+1+1
Binary
shifts
1. Left shift:
double
the number
2. Right shift:
halve
the number
Overflow
error
Result takes up more storage space than is possible
Character sets
ASCII: 8-bit, 256 characters
Unicode: 16-bit+, supports many languages
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