An Abacus

Babbage’s Difference Engine

Electronic Computers  1939–1944, Howard H. Aiken developed the Harvard Mark I—also known as the IBM ASCC.  Grace Hopper worked at Harvard on the Mark I, II, and III, and discovered the first computer bug.  Konrad Zuse worked secretly on his Z3 computer in Germany.

Vacuum Tubes

Programming ENIAC (U.S. Army photo)

Transistors

Integrated Circuit Integrated circuit

An Early PC

External System Components

Internal System Components System board Power connectors Adapter card Power supply Slots Drives

A System Board Expansion slots RAM CPU AGP slot Ports Drive interfaces

A Selection of CPUs

A Typical Memory Module

Interfaces Internal Interfaces External Interfaces

An Example of an Adapter Card Expands computer capabilities by enabling computer to connect to another computer over phone lines Circuit to connect to phone line PCI bus Phone line connection

A Hard Disk

A Floppy Disk and Drive Front view of a floppy disk drive Floppy disk

A CD-ROM Disc and Drive A CD-R disc An internal CD-ROM drive

Software  Software is the program code stored on a hardware disk.  Software is written in computer languages like Visual BASIC, C++, Cobol, assembler, and machine language.  Software can be divided into two categories—System software and Application software.

System Software

Application Software

Device Drivers Driver allows OS and device to communicate

Firmware Firmware is software stored in memory chips that retains data whether or not power to the computer is on.

Counting Marbles in the Decimal System How many? Pail holds 1,000 Can holds 100Cup holds 10

Counting Marbles in the Binary System How many?

Counting Marbles in the Hexadecimal System How many?Pail holds 256Can holds 16

Computer Values  Bit – A single binary digit  Byte – 8 bits  Nibble – 4 bits  Kilobyte (KB) – 1,000 bytes  Megabyte (MB) – 1,000,000 bytes