1. Chapter 4 Section 3

2. Expansion Slots and Expansion Cards
An expansion slot is a socket on the motherboard that can hold an adapter card.
An adapter card, also called an expansion card, is a circuit board that enhances functions of a component of the system unit and/or provides connections to peripherals, devices that connect to the system unit and are controlled by the processor in the computer.

3. Expansion Slots and Expansion Cards Continued
Some motherboards already include all the necessary capabilities and do not require adapter cards.
A few examples of adapters cards include: sound cards and video cards.
A sound card enables a computer to have input from a microphone.
A video card, also called a graphics card, enables the computer screen to be projected on a bigger screen.

4. PC Cards, Flash Memory Cards, and USB Flash Drives
PC cards are very small cards that add memory, storage, sound, network, and other capabilities for mobile computers.
Flash memory cards are very similar to flash drives but they are smaller. These are used primarily in smart phones and digital cameras.
USB flash drives transfer files and information to the flash drive to be read and edited by other devices that have USB ports.

5. Ports
Ports are the primary thing you have to have to connect a peripheral device. There are many types of ports.
The port used most often is the USB port. Computer mice, keyboards, flash drives, and many more things connect via USB.
The headphone port is used to hook up headphones for the sound output of your computer.

6. Special Purpose Ports
The four special purpose ports are MIDI, SCSI, IrDA, and Bluetooth. Special purpose ports are not included in typical computers.
The MIDI port connects the computer to a musical instrument, hence the acronym of Musical Instrument Digital Interface.
The SCSI port is a special high-speed parallel port. It allows you to attach SCSI peripherals such as disk drives and printers.

7. Special Purpose Ports Continued
The IrDA port uses infrared light wave technology to communicate with devices.
The Bluetooth port uses radio waves to transmit data between two devices.

8. Buses Bits travel on buses.
Buses allow the various devices both inside and attached to the system unit to communicate with each other.
Data bus: transfers actual data
Address bus: transfers info about where the data should reside in memory.