Zusammenfassung der Ressource
1.1 System Architecture V2
- System Buses
- Used to reduce the amount of
data collisions
- Data Bus - Carries instructions from the
main memory to the processor
- Address Bus -
Carries addresses
from processor to
main memory, it is
unidirectional
- Control Bus - Instructs
which data will be
travelling to and from
memory
- Internal
Components - The
Processor, Main
Memory (RAM,
ROM, EEPROM),
I/O Controllers,
Buses
- External Components - Keyboard, mouse,
printer, disk drives, I/O Devices/ I/O Ports,
Secondary Storage (External Hard drive)
- ROM - Read Only
Memory
- Bootstrap ladder is held in ROM, gives
the instruction to start up the
Operating System
- I/O Controllers - These are used to allow
an interface between a hardware device
external to the motherboard and the
processor.
- I/O Controllers are used for:
Keyboard, Mouse, Disk Drive
- More Cores = More instructions can be
processed simultaneously
- Embedded
Systems
- Hertz - Number Of Cycles
Per Second
- Processor Speed - Measured In Hertz
- Typical speeds have
spanned across MHz
and GHz
- A system within another
device e.g. central heating
system, dishwashers,
fridges, washing machines
- The purpose of the
CPU is to carry out
program
instructions.
- Each CPU is designed to execute a specific group of instructions. The CPU carries
out a series of functions in a continuous cycle
- CPU automatically checks cache for instructions
before it requests data from RAM. This saves
fetching the instructions and data repeatedly
from RAM – a relatively slow process.
- Cache - Small amount of
memory that is a part of the
CPU - closer to the CPU than
RAM. Used to temporarily hold
instructions and data that the
CPU is likely to reuse
- Motherboard - A circuit board that
connects the CPU to the memory The
CPU sits on the motherboard (also
called the logic board).
- Buses - Circuits on the motherboard
which connect the CPU to other
components..
- A bus moves instructions
and data around the
system
- The speed of a bus is measured in megahertz (MHz).
The faster the bus, the faster data is communicated.
The speed of the motherboard is defined by the bus
speed.
- Bridges - Manage how data + instructions are
transferred CPU, memory and other devices.
- ROM (read only memory) is non-volatile
Non-volatile means that its contents
cannot be changed and it retains its
memory after the computer is turned
off.
- Rom contains BIOS
which is the
firmware to the
motherboard. The
BIOS contains the
bootstrap
- It happens between turning on the power
and the computer beeping to say it is starting
to load the OS. This process is known as POST
(power on self test) on a PC.
- The boot sequence is
the computer's initial
start-up process. After
the boot, the OS
controls the CPU and
supplies the programs
to run.
- PROM - Made as blank ROM.
PROM chips can be bought
cheaply and programmed directly
by a programmer. They are not
rewritable so they can only be
programmed once.
- EEPROM (electrically erasable
programmable read-only memory) -
firmware can be easily updated, similar to
a rewriteable CD