1. The Computer System

2. Components of a computer
Basic Components
Input Devices
System Unit
Output Devices
Storage Devices
Other Components
Peripheral Devices
Communication Devices

3. Strengths of Computers
Speed
A computer can do billions of operations per second.
Reliability
Electronic components have very low failure rate.
Accuracy
Computer can process large amount of data and generate error-free results.

4. Communication/Connectivity
Storage
Computer can store enormous amount of data
Communication/Connectivity
A computer can share its input, process, output and storage with another computer.

5. Data Representation Bits Bytes
off or on digital value, short term for binary digits.
Bytes
a group of eight bits, a unique code can be assigned to 256 different data possibilities. (e.g represents the letter A.)

6. Coding Scheme
ASCII (American Standard Code for Information Interchange)
8 bits; used in many PC & minicomputer.
EBCDIC (Extended Binary Coded Decimal Interchange Code)
8 bits; used in Mainframe Computer
Unicode
16 bits
can represent > characters

7. 1. System Unit

8. Motherboard
A circuit board that contains most of the electronic components of the system unit.
Ports & Connectors
Expansion Slots (for display card, modem card…)
CPU Slot
BIOS Chip
DIMM Sockets for Memory

9. Components of System Unit
Motherboard
Central Processing Unit (CPU)
Memory
Upgrade sockets
Buses
Expansion Slot
Ports & connectors

10. The Central Processing Unit
It is the brain of a computer system
The CPU:
receives input.
interprets instructions provided by programs.
directs other components of the system to act.
processes data.
controls output.

11. The Central Processing Unit
Control Unit
ALU
Registers
Memory
Bus
CPU
Control Unit
It coordinates the flow of data and instructions. It contains a clock that generates a uniform stream of electrical pulses that synchronize the operating of the CPU and other computer components

12. The Central Processing Unit
Control Unit
ALU
Registers
Memory
Bus
CPU
Arithmetic and Logic Unit (ALU)
It performs calculations and comparisons of data.

13. The Central Processing Unit
Control Unit
ALU
Registers
Memory
Bus
CPU
Registers
They hold program instructions, data values, and memory locations as the computer executes a program.

14. The Central Processing Unit
Control Unit
ALU
Registers
Memory
Bus
CPU
Buses
They are electrical pathways that carry signal (bits) between a CPU’s components and outside devices.

15. Multiprocessing
Large computer systems, as well as newer workstations and network servers, frequently contain more than one central processing unit.
Multiple CPUs enable the computer to execute more than one instruction or process more than one program, at the same time.

16. Main Memory ROM CACHE RAM
Before programs are executed or data processed, they must first enter into main memory.
Main memory holds information read from disk or captured by input devices.
The CPU than moves information from the main memory into its registers for processing.
ROM
CACHE
RAM

17. Random Access Memory (RAM)
Integrated circuit containing data that can be read and written by the microprocessor or other devices.
Volatile - programs & data stored in RAM are erased when the power is off.

18. Read Only Memory (ROM)
Chips that store information or instructions that can be read and used, but cannot be changed.
Non-volatile - retains its contents even the power is turned off.
The instructions to start the computer are on a special chip known as a ROM BIOS chip (Basic Input/Output System).

19. Cache Memory
Cache memory is a specialized chip used with the computer's memory.
Cache chips are faster and more expensive than regular RAM chips.
The computer stores the most frequently used instructions and data in cache. Cache has a relatively small storage capacity but can significantly increase the system's speed.

20. In summary, memory accepts and holds program instruction and data
acts as the CPU’s source for data and instructions and as a destination for operation results
holds the final processed information until it can be sent to the desired output or storage devices, such as printer or disk drive