INSIDE THE
COMPUTER
Important
Terminology
􀂉 The unit of data size
􀂾 Bit : a binary digit that can have the value
0 or 1
􀂾 Byte : 8 bits
􀂾 Nibble : half of a bye, or 4 bits
􀂾 Word : two bytes, or 16 bits
􀂉 The terms used to describe amounts of
memory in IBM PCs and compatibles
􀂾 Kilobyte (K): 210 bytes
􀂾 Megabyte (M) : 220 bytes, over 1 million
􀂾 Gigabyte (G) : 230 bytes, over 1 billion
􀂾 Terabyte (T) : 240 bytes, over 1 trillion

INSIDE THE
COMPUTER
Internal
Organization of
Computers
􀂉 CPU (Central Processing Unit)
􀂾 Execute information stored in memory
􀂉 I/O (Input/output) devices
􀂾 Provide a means of communicating with
CPU
􀂉 Memory
􀂾 RAM (Random Access Memory) –
temporary storage of programs that
computer is running
􀂃 The data is lost when computer is off
􀂾 ROM (Read Only Memory) – contains
programs and information essential to
operation of the computer
􀂃 The information cannot be changed by use,
and is not lost when power is off
– It is called nonvolatile memory

INSIDE THE
COMPUTER
Internal
Organization of
Computers
(cont’) CPU
Memory
(RAM, ROM)
Peripherals
(monitor,
printer, etc.)
Address bus
Data bus

INSIDE THE
COMPUTER
Internal
Organization of
Computers
(cont’)
􀂉 The CPU is connected to memory and
I/O through strips of wire called a bus
􀂾 Carries information from place to place
􀂃 Address bus
􀂃 Data bus
􀂃 Control bus
CPU
Read/
Write
RAM
Address bus
Data bus
ROM Printer Disk Monitor Keyboard
Control bus