University of Sargodha, Lahore Campus Prepared by Ali Saeed

 What is Computer Organization & Assembly Language  BOOK: Assembly Language Programming and Organization of the IBM PC by Ytha Yu

 A typical Microcomputer System consist of ◦ System Unit ◦ Keyboard ◦ Display Screen ◦ Disk Drives  System Unit often referred as ‘The Computer’  Keyboard, Display Screen, and Disk Drivers are called i/o Devices or Peripheral Devices, or simple Peripherals.

 Integrated Circuit (IC) chips are used to construct computer circuits  Each IC may contain hundreds or thousand of transistors  These IC are called digital circuits  It work on discrete levels of voltage  Low voltage represent 0 and high voltage represent voltage 1  0 and 1 called binary digits or bits

 Computer Circuit consist of three parts ◦ Central Processing Unit (CPU) ◦ Memory Circuits ◦ I/O Circuits  CPU is single processor chip called microprocessor  CPU is the brain of computer, and it controls all operations  CPU use memory circuits to store information  CPU use I/O circuit to communicate with IO

 System Unit contain a main board called System board or Mother board  System board contain Microprocessor, memory, expansion slots etc…

 Information process by computer store in the memory  Memory circuits are usually organized into groups that can store 8 bit of data called memory Byte  It is identified by a number called Address  Data stored in memory byte called Contents  No. of contents are 8 bit but address depend on processor

 8086 processor use 20 bit Address  processor use 24 bit Address  Two bytes form a word  The lower address of two memory bytes are use

 1 Byte = 8 Bits 1KB = 1024 Bytes 1MB = 1024KBs 1 GB = 1024 MBs 1TB = 1024Gbs

 1000 kbit kilobitkilobit  Mbit megabit  Gbit gigabitgigabit  Tbit terabitterabit  Pbit petabitpetabit  Ebit exabitexabit  Zbit zettabitzettabit  Ybit yottabityottabit

 Bit position is use to read bytes  It starts from right to left  At most right position it starts from 0  Byte Positions

 Processor can perform to two kinds of operations  Read/ Fetch the contents of a location  Store or write data at location

 Random Access Memory (RAM) ◦ Program instructions and data normally loaded into RAM ◦ The content of RAM lost, when machine is turned off  Read Only Memory (ROM) ◦ ROM circuit retain their value even when power is off ◦ ROM is used by computer manufacturers to store system programs ◦ These programs are called firmware

 Processor communicate with other components using signals that travel on wires called Bus  There are three kinds of buses ◦ Address Bus ◦ Data Bus ◦ Control Bus

 Thanks