Registers are temporary storage areas within the CPU that can hold instructions and data during processing. They are faster than main memory. An address identifies the location of data in memory. A bus is a communication pathway that allows different computer components to transfer data. There are internal and expansion buses. Registers include the memory data register, current instruction register, and program counter. Booting loads an operating system from secondary storage into RAM to start a computer, while shutting down closes programs to turn off power in an orderly fashion.

1. HHCJ AMUMARA
COMPUTER STUDIES LECTURE NOTE –SS2
(NOTE 001)

2. COMPUTER DATA CONVERSION
Data conversion is the conversion of computer data from one format to another
DEFINITION OF REGISTERS, ADDRESS AND BUS:
REGISTERS :
Registers are temporary storage areas for instruction or data.
It can also be defined as a special, high-speed storage area within the CPU.
They are not part of the memory; rather they are special additional storage locations
that offer the advantage of speed.
Register works under the direction of the control unit to accept, hold and transfer
instruction or data and perform arithmetic or logical comparison at high speed.
Register are the fastest memory available for use in the PC, because they are hard-
wired right into the processor logic.

3. • Address: A memory address is an identifier for
a memory location, at which a computer
program or a hardware device can store data
and later receive it.
• Bus: A bus, in computing, is a set of physical
connections (cables, printed circuits, etc.)
which can be shared by multiple hardware
components in order to communicate with
one another.
• The purpose of buses is to reduce the number
of "pathways" needed for communication
between the components, by carrying out all
communications over a single data channel.

4. TYPES OF BUS
• There are generally two buses within a computer:
• 1. Internal Bus: The internal bus (sometimes called the
front-side bus, or FSB for short). The internal bus allows
the processor to communicate with the system's
central memory (the RAM).
• 2. Expansion Bus: The expansion bus (sometimes
called the input/output bus) allows various
motherboard components (USB, serial, and parallel
ports, cards inserted in PCI connectors, hard drives, CD-
ROM and CD-RW drives, etc.) to communicate with one
another. However, it is mainly used to add new devices
using what are called expansion slots connected to the
input/output bus.

5. TYPES OF REGISTER AND FUNCTIONS
• There are many types of registers; some of these are given
below:
• 1. Memory Data Register (MDR): This register contains
the data to be stored in the computer storage or the data
after a fetch from the computer storage.
• 2. Current Instruction Register (CIR): CIR stores the
instruction currently being executed or decoded.
• 3. Memory Address Register (MAR): MAR holds the
memory address of data and instruction.
• 4. Program Counter (PC): PC commonly called instruction
pointer (IP) and sometimes called instruction address
register. It is a register that holds the address of the memory
location of the next instruction when the current instruction
is executed by the microprocessor.
• 5. Accumulator Register: This register is used for storing
the results that is produced by the system.

6. DIFFERENCES BETWEEN REGISTERS AND
MAIN MEMORY

7. FUNCTIONS OF A REGISTER
1. Holds the address of memory where CPU wants to read or write data
2.Holds the contents of data instruction read from or written in
memory
3.Used to specify the address of a particular I/O device
4.Used for exchanging data between the I/O module and the processor
5.Used to store the address of the next instruction to fetch for
execution
6.It stores current instruction being executed or coded
7.It allows the bits of its content to be moved to left or right (shift
register)
8.It holds the memory addresses of data and instruction during
execution phase
9.It is used to store the result produced by the system

8. STEPS INVOLVED IN HOW A COMPUTER
CONVERTS DATA TO REQUIRED
INFORMATION
Fetch-Execute Cycle
• The steps in the processing cycle are as follows:
• a. Fetch the next instruction: The program counter contains the address of the
next instruction to be executed; the control unit goes to the address in the
memory specified in the program counter, make a copy of the contents and
places the copy in the instruction register.
• Decode the Instruction: In order to execute the instruction in the instruction
register, the control unit has to determine what the instruction is.
• Get Data If Needed: It may be that the instruction to be executed requires
additional memory accesses in order to complete its task. If this is the case, the
control unit must get the content of the memory location.
Execute the Instruction: Once an instruction has been decoded and any data
fetched, the control unit is ready to execute the instruction. Execution involves
sending signals to the arithmetic/logic unit to carry out the processing. When
the execution is complete, the cycle begins again.

9. FACTORS AFFECTING THE SPEED OF DATA TRANSFER
The amount of RAM memory.
The speed and generation of your CPU (the
system clock)
The size of the Register on your CPU.
The Bus width.
The Bus speed.
The amount of Cache memory.

10. BASIC COMPUTER OPERATIONS
BOOTING AND SHUTTING DOWN PROCESS
• Description of Booting:
• Booting is the process of starting a computer. It is a
process to ready the computer system for performing
any task.
• Botting can be initiated by hardware such as a button
press, or by a software command.
• Booting is a process or set of operations involved in
loading and starting the operating system from the point
in which the user switches on the power button
Note:Restarting a computer also is called rebooting

11. BOOTING PROCESS (STEPS INVOLVED IN
BOOTING)
• Generally booting includes a number of tasks. These tasks are performed to
make the computer system ready. These tasks can be sequenced as:
 When the power gets ON, memory testing (RAM test) is performed.
 When this is OK, a boot loader program checks all H/W attached with
computer system. Such as keyboard, hard disk, CPU, etc.
 After listing H/Ws, the boot loader program searches for operating system in
secondary storage device. If it found, it calls the main program of operating
system and loads operating system into RAM.
 After successfully loading the operating system, it shows the prompt. If the
operating system is DOS, then the prompt may be A :>, B :>, or C :>. If it is
Windows then a desktop is displayed with Start Button.

12. TYPES OF BOOTING
• Booting can be done is two ways:
1. Cold Booting or Soft Booting
2. To perform a cold boot means to start up a computer
that is turned off. A cold boot is typically performed by
pressing the power button on the computer.
3. Warm Booting or Hard Booting
When CTRL+ALT+DEL keys are pressed
simultaneously then warm booting is performed.
Note:The first step of booting process (memory test 0 is
skipped, when this booting is applied. Reset button can
also be used for warm booting).

13. NOTE
• TAKE NOTE OF THE FOLLOWING:
• Cold booting is also called hard booting, cold
start, dead start.
• Warm booting is also called soft booting.

14. SHUTING DOWN A COMPUTER
• Shut down is the process of closing all software
programs in preparation to turn off a computer's
power.
• The operating system is the last program to be closed
as part of a computer's shut down process.

15. IDENTIFICATION OF FEATURES ON A DESKTOP
• ON THE COMPUTER DESKTOP ARE ICONS
• Icons are small pictures that represent
files, folders, programs, shortcuts, and
other items. When you first start
Windows, you will see at least one icon
on your desktop.

16. EXAMPLE OF DESKTOP ICONS

17. DESKTOP

18. DIFFERENCE BETWEEN COLD BOTTING
AND WARM BOOTING
• The main difference between cold and warm booting is
that the cold booting is the process of starting up the
computer that is turned off while warm booting is the
process of restarting the computer without interrupting
power.
• Cold booting is initialized by pressing Power button while
warm booting is initialized by the operating system.
• Cold booting includes power on self-test while warm
booting does not include power on self-test (POST).
• Cold booting performs more complete reset of the system
..warm booting does not perform complete reset of the
system.

19. N/B:
• Initialized by
• While cold booting is initialized by pressing the power button on the
computer, warm booting is initialized by the operating system.
• Synonyms
• Cold booting is also called hard booting, cold start, dead start. Warm
booting is also called soft booting.
• Reset
• A cold booting performs a more complete reset of the system than
warm booting. This is another difference between cold and warm
booting.
• Power On Self-Test
• Furthermore, cold booting includes power on self-test (POST) while
warm booting does not include POST.

20. STAY AT HOME, STAY SAFE , BE
POSITIVE. (MAY 12,2020)