1. created by jithesh B nair systems
manager people institute of
management studies munnad
Computer Hardware and Flow of
Information
2. What is a Computer?
• Computer
– Device capable of performing computations and making logical
decisions
– Computers process data under the control of sets of instructions
called computer programs
– Personal computers: economical enough for individual
– Distributed computing: computing distributed over networks
– Client/server computing: sharing of information across computer
networks between file servers and clients (personal computers)
3. What is a Computer? (cont.)
• Computer Hardware
–Various devices comprising a computer:
–Keyboard, screen, mouse, disks, memory, CD-ROM, and
processing units
High-level
Language
Assembly
Language
Firmware
Machine
Code
Hardware
User
Application
Software
OS
4. What is a Computer? (cont.)
• Computer Software
– Computer Programs that run on a computer, including
• Operation System (OS)
• Application Software
• Computer Language
High-level
Language
Assembly
Language
Firmware
Machine
Code
Hardware
User
Application
Software
OS
5. Computer Architecture
A Typical Von-Neumann Architecture
Example:
1. Input unit
2. Output unit
3. Memory unit
4. Arithmetic and logic unit (ALU)
5. Central processing unit (CPU)
6. Secondary storage unit
Control Circuit
(ex: PC: Program Counter)
ALU
Memory I/O
CPU
6. Computer Architecture (cont.)
Five major operations performed by a computer system:
1. Input
• Obtains information from input devices (keyboard, mouse)
1. Storage
• Primary
o or main memory or internal memory / memory
o the only one directly accessible to the CPU.
o The CPU continuously reads instructions stored there and
executes
them as required.
o Eg: ROM (Read Only Memory): CMOS, EPROM
o RAM (Random Access Memory): SRAM, DRAM, SIMM, DIMM
• Secondary
o known as external memory or auxiliary storage
o Not directly accessible by the CPU
o Eg: Hard disk, flash memory, floppy disks
7. Computer Architecture (cont.)
Six logical units in every computer (cont):
3. Processing
4. Output
• Outputs information (to screen, to printer, to control other devices
3. Control
8. Computer Architecture (cont.)
Basic computer functional units control
• Arithmetic and logic unit (ALU) – part of CPU
Performs arithmetic calculations (addition, subtraction...)
and logic decisions
• Control unit (CU) - part of CPU
Supervises and coordinates the other sections of the
computer
9. Computer Architecture (cont.)
• Central Processing Unit (CPU)
– “brain” of a computer, consisting of
• Arithmetic and logic unit (ALU): performs arithmetic
calculations (addition, subtraction...) and logic decisions (>,
<, =, ...)
• Control Unit (CU): decodes each machine instruction and
sends signal to other components for carrying out the
instruction.
– An integrated circuit (IC) that is a full central processing unit is
called a microprocessor (µp); a CPU’s current instruction and data
values are stored temporally inside the CPU in special high-speed
memory location called registers.
– CPU speed: ? MHz (M: Mega = 106
, Hz=1/sec);
10. Computer Architecture (cont.)
• Memory
– A large collection of circuits, each capable of storing bit
– Cells (words): manageable units; typical size is 8 bits (1 byte),
some machines are 16 bits (2 bytes) and some are 32 bits or 64
bits
• Byte (8 bits), KB (kilobyte, 103
≈ 210
bytes), MB (Megabyte, 106
≈ 220
bytes), GB (Gigabyte, 109
≈ 230
bytes). Note: k ≠ K
because 1000 ≠ 1024.
11. Computer Architecture (cont.)
– Computer memory is comparable to a collection of numbered
mailboxes. To identify individual cells in a machine’s main
memory, each cell is assigned a unique name, called its address
– The organization of byte-size memory cell
...01001000 01100101 01101100 0110111101101100 00101110
H e l l o ,ASCII
...Data
Address 0000 0101 0000 0110 0000 0111 0000 1000 0001 0001 0001 0010
Address Bus
Data Bus
0 0 0 0 0 1 0 1 Low-order endHigh-order end
Least Significant Bit (LSB)Most Significant Bit (MSB)
12. A Typical Von-Neumann Architecture
Example:
1. Input unit
2. Output unit
3. Memory unit
4. Arithmetic and logic unit (ALU)
5. Central processing unit (CPU)
6. Secondary storage unit
Control Circuit
(ex: PC: Program Counter)
ALU
Memory I/O
CPU
13. Computer’s Bus System
• 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.
• think of a bus as a highway on which data travels within a computer.
14. Computer’s Bus System (cont..)
• Purpose of buses = to reduce the number of "pathways"
needed for communication between the components, by
carrying out all communications over a single data
channel.
15. Types of Computer’s Bus
• There are generally two buses within a computer:
• Internal bus (system bus)
– Allows the processor to communicate with the system's central
memory (the RAM).
• External bus (expansion 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.
16. Types of External Buses
• There are five major types of external bus’s found on
the common motherboard.
– ISA (Industry Standard Architecture)
• This bus is the low speed work horse of the system.
• commonly find a Sound Card hooked up this type BUS.
– PCI (Peripheral Component Interconnect)
• Supports 32-64 bit bus and is the reigning standard of
external buses.
• Fast
• slowly making the ISA fade away. Go with a PCI Bus Card
when possible.
17. Types of External Buses (cont…)
– AGP (Accelerated Graphics Port)
• This Bus provides from 2 to 4 times the speed of the PCI
• used for video expansion only.
• great way to go and takes a lot of stress off the CPU, thus
gaining in performance all the way around.
– USB (Universal Serial Bus)
• allows to hook up to 127 devices.
• probably going to wipe out PS/2 ports and more.
• Allows to hot swap devices or plug and unplug devices while
system is running.
• a great feature and is incorporated on most new
motherboards.
18. Types of External Buses (cont…)
– IDE (Intelligent Drive Electronics)
• used mostly for disk drives
• connects up to two devices on one connection.
• More than likely hard drive and CD-ROM are connected through
this type bus.
