1. An Abacus

2. Babbage’s Analytical Engine  Punched cards  First used in Jacquard Loom (1801) to store patterns for weaving cloth  Stored programs in Babbage’s Analytical Engine  Popular through the 1970’s  Gear positions

3. The Mark I computer

4. Modern Day PC

5. What’s a Comput-er ?

6. Computer Science Terminology  Data: Information served as input to programs and algorithms.  Algorithm: A set of steps that defines how a task is performed  Programming: Process of developing a program  Program: A representation of an algorithm  Hardware: Equipment

7. An Algorithm for River Crossing 9 Men and 2 boys wish to cross a river using an inflatable raft that will at most carry either one man or the two boys. How many times must the boat cross the river to accomplish this goal?

8. Central Questions of Computer Science

9. Computer Science  The science of algorithms  Draws from other subjects, including  Mathematics  Engineering  Psychology  Business Administration

10. Types of Computers  Supercomputers  Mainframe computers  Minicomputers  Microcomputers Microcomputers Page 10

11. Personal Computers  First used by hobbyists  IBM introduced the PC in 1981  Accepted by business  Became the standard hardware design for most desktop computers  Most PCs use software from Microsoft

12. Four Types of Microcomputers  Desktop Desktop  Notebook or laptop Notebook or laptop Notebook or laptop  Tablet PC Tablet PC Tablet PC  Handheld Handheld Page 11

13. What Makes Up a Computer? Page 11

14. What Makes Up a Computer? A computer consists of a central processing unit (CPU), memory, hard disk, floppy disk, monitor, printer, and communication devices.

15. CPU The central processing unit (CPU) is the brain of a computer. It retrieves instructions from memory and executes them. The CPU speed is measured in megahertz (MHz), with 1 megahertz equaling 1 million pulses per second. The speed of the CPU has been improved continuously. If you buy a PC now, you can get an Intel Pentium 4 Processor at 3 gigahertz (1 gigahertz is 1000 megahertz).

16. Central Processing Unit  Central Processing Unit (CPU) or processor  Arithmetic/Logic unit versus Control unit  Registers  General purpose  Special purpose  Mounted on the motherboard  Connected to other devices via bus

17. CPU and main memory connected via a bus

18. Speak Machine  Machine instruction: An instruction (or command) encoded as a bit pattern of 0’s and 1’s recognizable by the CPU  Machine language: The set of all instructions recognized by a machine

19. Machine Instruction Types  Data Transfer: copy data from one location to another  Arithmetic/Logic: use existing bit patterns to compute a new bit patterns  Control: direct the execution of the program

20. Program Concept - A program is a set of machines instructions arranged in a purposeful way and stored in main memory. - CPU can then extract the instructions and execute them. - Program is executable and can be altered easily.

21. Memory Memory is to store data and program instructions for CPU to execute. A memory unit is an ordered sequence of bytes, each holds 8 bits. A program and its data must be brought to memory before they can be executed. A memory byte is never empty, but its initial content may be meaningless to your program. The current content of a memory byte is lost whenever new information is placed in it.

22. Main Memory Cells  Cell: A unit of main memory (typically 8 bits which is one byte)

23. How Data is Stored? Data of various kinds, such as numbers, characters, and strings, are encoded as a series of bits (zeros and ones). Computers use zeros and ones because digital devices have two stable states, which are referred to as 0 and 1 by convention. No two data can share or split a same byte. A byte is the minimum storage unit.

24. Memory Terminology  Random Access Memory (RAM): Memory in which individual cells can be easily accessed in any order  Dynamic Memory (DRAM): RAM composed of volatile memory

25. Measuring Memory Capacity  Kilobyte: 2 10 bytes = 1024 bytes  Example: 3 KB = 3 × 1024 bytes  Sometimes “kibi” rather than “kilo”  Megabyte: 2 20 bytes = 1,048,576 bytes  Example: 3 MB = 3 × 1,048,576 bytes  Sometimes “megi” rather than “mega”  Gigabyte: 2 30 bytes = 1,073,741,824 bytes  Example: 3 GB = 3 × 1,073,741,824 bytes  Sometimes “gigi” rather than “giga”

26. Mass Storage  On-line versus off-line  Typically larger than main memory  Typically less volatile than main memory  Typically slower than main memory

27. Storage Devices Memory is volatile, because information is lost when the power is off. Programs and data are permanently stored on storage devices and are moved to memory when the computer actually uses them. There are three main types of storage devices:Disk drives (hard disks and floppy disks), CD drives (CD-R and CD-RW), and Tape drives.

28. A magnetic disk storage system

29. Magnetic tape storage

30. CD storage

31. Device Communication  Controller: An intermediary apparatus that handles communication between the computer and a device  Specialized controllers for each type of device  General purpose controllers (USB and FireWire)  Port: The point at which a device connects to a computer

32. Controllers attached to a machine’s bus

33. Communication Devices A regular modem uses a phone line and can transfer data in a speed up to 56,000 bps (bits per second). A DSL (digital subscriber line) also uses a phone line and can transfer data in a speed 20 times faster than a regular modem. A cable modem uses the TV cable line maintained by the cable company. A cable modem is as fast as a DSL. Network interface card (NIC) is a device to connect a computer to a local area network (LAN). The LAN is commonly used in business, universities, and government organizations. A typical type of NIC, called 10BaseT, can transfer data at 10 mbps (million bits per second).

34. Data Communication Rates  Measurement units  Bps: Bits per second  Kbps: Kilo-bps (1,000 bps)  Mbps: Mega-bps (1,000,000 bps)  Gbps: Giga-bps (1,000,000,000 bps)  Bandwidth: Maximum available rate

35. Output Devices: Monitor The monitor displays information (text and graphics). The resolution and dot pitch determine the quality of the display.

36. Bits and Bit Patterns  Bit: Binary Digit (0 or 1)  Bit Patterns are used to represent information.  Numbers  Text characters  Images  Sound  And others

37. The Binary System The traditional decimal system is based on powers of 10. The Binary system is based on powers of 2.

38. Number Systems 0, 1 0, 1, 2, 3, 4, 5, 6, 7 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F binary octal decimal hexdecim al