Computers require
an input hardware,
processing
hardware and
output hardware.
CPU
executes programs
using the
fetch-decode-execute
cycle
Memory
Stores program
operations and data
while the program is
being executed. Types:
Registers, cache, RAM,
ROM and Virtual
Memory
Storage
Stores
programs and
files long term,
even when not
in use. Types
include: USB, SD
Cards,
Hard-Drives and
SSDs
Graphics
Most computers have
a separate GPU and
CPU
Using the GPU to render
images, frees up the CPU for
other tasks
Performance
Benchmarking
A test used to access the
performance of a
computer. Different types
of software are used
depending on the
computers purpose.
CPU speed (cycles per second) measured in Hertz
GHz
MHz
KHz
Hz
CPU and Memory
Factors that affect performance
Cores
CPU can contain one or
more processing units
(cores). A core contains a
ALU, Control Unit and
Registers.
Cores communicate
through channels
therefore doubling cores
does not double speed
Clock Speed
The clock speed - also known as clock
rate - indicates how fast the CPU can
run. This is measured in megahertz
(mHz) or gigahertz (gHz) and
corresponds with how many
instruction cycles the CPU can deal with
in a second.
Cache Size
Cache is a small amount of
memory which is a part of
the CPU - closer to the CPU
than RAM. It is used to
temporarily hold
instructions and data that
the CPU is likely to reuse.
The CPU control unit
checks the cache for
instructions before the
RAM.
Larger the Cache = the more
data can be stored closer to
the CPU
L! - part of the CPU
chip, smallest and
fastest to access
(between 8KB and
64KB
L2/3 - larger, extra
cache built between
the CPU and RAM.
More L2/3 = faster a
computer can run
Processor Type
CISC
Complex Instruction Set Computing
Used by most
laptops/desktops - made by
Intel/AMD
RISC
Reduced Instruction
Set Computing
Used in tablets/smartphones
Differences
RISC have less
instructions. RISC
more efficient at
simpler tasks
Physical Size -
CISC are larger
and require
more silicon
Speed - RISC
run at a lower
clock speed
Energy Consumption - CISC
are larger and therefore
use more energy
Design - RISC combines
architecture onto one chip
(SOC), whereas CISC are
built seperatly a system
with heat sinks and fans
- RISC do not.
Cost - RISC use less
power and are
cheaper to make
Bridges
Bridges manage how data and
instructions are transferred between
devices
Memory
Memory is the area where the computer
stores or remembers data. Memory
provides the CPU with its instructions.
AKA Primary Storage
Closer to CPU = quicker the CPU can access
instructions
VOLATILE
Only stores information to run programs
while the PC is on. Reset when the PC is
turned off. Requires electricity to store data
using transistors and capacitors
NON-VOLITILE
Retains data even when the computer is off.
Examples in old computers: paper, punched tape
and floppy disks
Latency is the time for
components to
respond to a request