Chapter 3 Peter Norton’s  Introduction to Computers Interacting with Your Computer

Input Devices: Keyboard Mouse Trackball Trackpad Pen Touch Screen Bar Code Reader Image Scanner Microphone Video

Factors Affecting Monitors: Size Resolution Refresh rate Dot pitch

Size is measured diagonally. Resolution = no. of pixels (i.e x 768) Image clarity or sharpness Refresh rate = number of Times persecond that the electron gun scans every pixel on the screen frames in one second The picture is scanned from left to right and from top to bottom. One complete set of scan lines is called a frame. 1 pixel in a color monitor

Flat-Panel Monitors: LCD (Liquid Crystal Display) (Notebooks use LCD displays)

Types of Printers: Ink JetHome and Offices LaserHome and Offices Dot-MatrixHome and Office PlotterCommercially used for printing of sign boards or large images

Ink jets are popular because of their relatively low cost and color capability.

Paper is given a static charge Laser beam Heat roller bonds toner to paper Toner transferred from drum to paper Rotating mirror Laser transfers image to drum Laser printers are faster and capable of high resolution.

Printer Criteria: Image QualityDPI SpeedPPM Initial CostNormal Cost of OperationNormal

Machine Cycle Fetching CU receives command / data from memory Decoding CU breaks down commands into instructions Executing After command execution CPU converts them into microcode Storing CPU stores results into memory

Types of Interfaces: Serial Parallel SCSI (Small Computer System Interface)

Bit 0Start bitBit 1Bit 2Bit 3Bit 4Bit 5Bit 6Bit 7Stop Bit RS232 Driver To modem Transmitter Receiver Control Serial data transmission is relatively slow! The serial ports transfer data one bit at a time.

Transmitter Receiver Control To printer The parallel port transfers data one byte at a time. Drivers

A SCSI card can be plugged into an expansion slot. SCSI devices can be daisychained.

The major computer system components (processor, main memory, I/O modules) need to be interconnected in order to exchange data and control signals A bus is a communication pathway connecting two or more devices A bus that connects major computer components (processor, memory, I/O) is called a system bus. Bus = a shared transmission medium. Only one device at a time Can successfully transmit. shared system bus consisting of multiple lines a hierarchy of buses to improve performance. Key design elements for buses include: Arbitration, Timing, width

Program A sequence of (machine) instructions (Machine) Instruction A group of bits that tell the computer to perform a specific operation (a sequence of micro-operation) The instructions of a program, along with any needed data are stored in memory The CPU reads the next instruction from memory It is placed in an Instruction Register (IR)

A computer instruction is often divided into two parts An opcode (Operation Code) that specifies the operation for that instruction An address that specifies the registers and/or locations in memory to use for that operation In the Basic Computer, bit 15 of the instruction specifies the addressing mode (0: direct addressing, 1: indirect addressing) Since the memory words, and hence the instructions, are 16 bits long, that leaves 3 bits for the instruction’s Opcode Address Instruction Format I 11 Addressing mode

Learning Objectives: Chapter 3 Review List at least three common input and output devices. Name the processes a video monitor uses to displays images. Name the components of a mouse and list the common techniques used to maintain a mouse. Name three types of printers and list the advantages and disadvantages of each. Explain how input and output devices communicate with the other parts of the computer.