1. C_ITCO011/C_ITCO111 LECTURER: E.DONDO
Computer Systems
C_ITCO011/C_ITCO111
LECTURER: E.DONDO

2. Unit 2:
System Components

3. Signaling
Data is transmitted by a computer via electrical signals which are stored in components called ‘transistors’.
The electrical pathways that carry these signals are referred to as ‘buses’.
Signaling methods can either be:
differential or single-ended
serial or parallel
digital or analogue

4. Serial vs Parallel data transfer /transmission
parallel data transfer refers to the type of data transfer in which a group of bits are transferred simultaneously .
serial data transfer refers to the type of data transfer in which a group of data bits are transferred one bit at a time.
so generally, the amount of data transferred serially is less that the data transferred in parallel per second.
serial data transfer requires less pins/cables so the data can be transmitted over longer distances & smaller hardware can be used.

5. Single-ended vs Differential signaling
Single-ended signaling 
is the simplest and most commonly used method of transmitting electrical signals over wires.
One wire carries a varying voltage that represents the signal, while the other wire is connected to a reference voltage, usually ground.
advantage of single-ended over differential signaling is that fewer wires are needed to transmit multiple signals
Differential signaling 
method of transmitting information electrically with two complementary signals sent on two paired wires, called a differential pair.
this technique improves resistance to electromagnetic noise compared with use of only one wire and an un-paired reference (ground).
can be used for both analog signaling and digital signaling

6. Analog vs Digital signaling
-analog is a continuous electrical signal
-information is translated into electric pulses of varying amplitude.
- best suited for audio and video transmission.
-digital is a non-continuous electrical signal.
-translation of information is into binary format (0 or 1) where each bit is representative of two distinct amplitudes.
- best suited for computing and digital electronics.

7. Data Units computers work with binary data.(base 2)
the basic unit of data storage is a bit
1 bit = 0 or 1
8 bits = 1 byte
1024 bytes = 1 KB
1024 KB = 1 MB
1024 MB = 1 GB
1024 GB = 1 TB
Binary values can be converted to:
decimal (base 10)
hexadecimal (base 16)

8. Ports
External ports
- I/O ports allow for additional devices to be connected to a PC.
PC99 connectors
PC99 is standard which defines colour codes for external ports e.g. PS/2 mouse (green) ,PS/2 keyboard (purple)
Legacy port types
Ports can be male, which have pin connectors, or female, which have hole connectors.

9. PC99 Colour codes
Male and female connectors

10. Types of Ports PS/2 ports Serial ports Parallel ports
PS/2 is a serial bus.
used to connect a keyboard and mouse.
Serial ports
aka RS-232 port or a communication ‘COM’ port.
connects to modems, printers .
Parallel ports
also known as the ‘printer’ or ‘Centronics’ port.
data is transferred simultaneously over eight wires .
VGA(Video graphics array) ports
is the standard analogue video interface for PC devices.
interface carries red, green and blue (RGB) component video signals.

11. HDMI and other display ports
SCSI
uses a parallel data stream with hardware handshaking(uses handshake signals between devices ) and control signals(parity error-checking).
supports a variety of devices e.g. dot-matrix printers to scanners, plotters
IEEE 1394 (Firewire)
is a serial bus interface standard for high-speed communications and isochronous real-time data transfer.
FireWire devices are
Plug and Play- the OS auto-detects a new device and asks for the driver disk.
Hot-pluggable - they can be connected and disconnected at any time, even with the power on.
HDMI and other display ports
only carries a digital signal; it does not support analogue signals.
supports both video and audio digital streams as well as remote control and digital content protection.
Other display ports
Composite video
S-video
Component (RGB) video

12. USB(Universal serial bus) ports.
USB(Universal serial bus) ports
USB was designed to standardize the connection of computer peripherals (e.g. keyboards, disk drives) to PCs.
Used to communicate and also to supply electric power.
USB supports hot swapping i.e. it can detect and configure a hot swappable device without requiring a restart.

13. Peripheral devices Input devices Output devices
peripherals that enable a user to enter data and select commands.
Mouse
Digital cameras
Scanners
Biometric devices
Joysticks/game pads
Bar code readers
Touch sensitive screens
Output devices
peripheral devices that are capable of presenting information from a computer.
Monitors
produce soft copies of the output.
Printers
produce hard copies of the output.
Can be impact printers(e.g. dot matrix) or non-impact printers(e.g. laser)

14. How much do you remember ?
1.Explain
parallel and serial communication.
analog and digital transmission.
2. Briefly discuss the various types of mouse(s).