Lecture #2

Primary Components

Buses• A bus is a set (group) of parallel lines that information

(data, addresses, instructions, and other information) travels on inside a computer. Information travels on buses as a series of electrical pulses, each pulse representing a one bit or a zero bit.

• The size or width of a bus is how many bits it carries in parallel. Common bus sizes are: 4 bits, 8 bits, 12 bits, 16 bits, 24 bits, 32 bits, 64 bits, 80 bits, 96 bits, and 128 bits.

• The speed of a bus is how fast it moves data along the path. This is usually measured in Mega Hertz (MHz) or millions of times a second.

Sockets & Ports

• Computer sockets are the built-in interfaces on motherboards that accept various hardware components. When compatible devices are plugged into computer sockets, they communicate with the system to provide functionality. Dial-up modems, graphics cards and sound cards are just some examples.

Motherboard• The main circuit board of a microcomputer.

The motherboard contains the connectors for attaching additional boards. Typically, the motherboard contains the CPU, BIOS, memory, mass storage interfaces, serial and parallel ports, expansion slots, and all the controllers required to control standard peripheral devices, such as the display screen, keyboard, and disk drive.

RAM

• Random Access Memory, a type of computer memory that can be accessed randomly; that is, any byte of memory can be accessed without touching the preceding bytes. RAM is the most common type of memory found in computers and other devices, such as printers.

• RAM is volatile memory.

Types of RAM

There are two different types of RAM:• DRAM (Dynamic Random Access Memory)• SRAM (Static Random Access Memory).

Types of RAM

• DRAM needs to be refreshed thousands of times per second while

• SRAM does not need to be refreshed, which is what makes it faster than DRAM.

• Both types of RAM are volatile, meaning that they lose their contents when the power is turned off.

ROM

• There is a type of memory that stores data without electrical current; it is the ROM (Read Only Memory) or is sometimes called non-volatile memory as it is not erased when the system is switched off.

Types of ROM

• PROM (Programmable Read Only Memory)• EPROM (Erasable Programmable Read Only

Memory)• EEPROM (Electrically Erasable Read Only

Memory .

CHIP

• A small piece of semiconducting material (usually silicon) on which an integrated circuit is embedded There are different types of chips. For example, CPU chips (also called microprocessors)

CARDS

• Computer card is an expansion device that provides an existing computer with certain added capabilities. What these capabilities are depends of course on the computer card. Some examples of popular computer cards include high speed serial port cards, USB cards, fire wire cards, and parallel cards.