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Learning About Your Computer Hardware Monit or System Unit (CPU) Keybo ard Mous e Floppy Disk drive
Another way of looking at a computer is the Box that contains everything - the main system board (motherboard) - CPU: Central processing unit - BIOS: Basic Instruction Operating System - RAM (Random Access Memory) - System Bus - Expansion slots
Central Processing Unit (CPU) is the “brain” of the computer. It has two components: - The Central Unit or Control Unit and - The Arithmetic Logic Unit (ALU).
CPU=Control Unit +ALU The Control Unit: - coordinates the operation of all the other components. The ALU: - all arithmetic calculations and logical decisions.
CPU and Programs Program is an instruction to the CPU Compatibility Not all software is compatible with any given CPU. New processors of the same family run older software. New software is not usually compatible with old processors.
CPU Speed Speed is determined by the internal clock of a computer. Speed of a computer’s CPU is measured in Megahertz. The architecture of a computer determines its speed. One cannot compare speeds across different architectures.
Communication devices Control Unit Arithmetic & Logic Unit Memory Unit Secondary storage Inp ut Unit Out put Unit Dat a Contr ol CP U
Primary Storage Section Inpu t Stor age Area Outp ut Stor age Area Progr am Stora ge Area Worki ng Storag e Area Arithmetic and Logic Unit
Memory Unit ( หน่วยความจำ ) bit - the smallest unit of binary digit byte - a group of 8 bits word - a group of bits and may represent a number, an instruction code, or any other binary-coded information. Each word in memory is assigned an identification number, called an address, starting from 0 and continuing with 1, 2, 3, up to 2 k - 1 where k is the number of address line เช่น 16-bit word = 2 bytes
A Bit About Bits - In genaral using n bits, it is possible to represent upto 2x2x2x2x2 ….. (n times) values, 2 n - e.g., 3 bits allow us to distinguish between 8 tings 4 bits ---->16 things 5 bits ---->32 8 bits (1 byte)----> 256 12 bits ----> 4096 16 bits ----> 65536 32 bits ----> over 4 billion things
การบอกขนาดของหน่วยความจำ KB (kilobyte) = 2 10 = 1,024 byte M (megabyte) = 2 20 = 1,048,576 byte G (gigabyte) = 2 30 T (Terabyte) = 2 40 เช่น 64K = 64 x 1024 byte
Primary Storage: Computer Memory RAM (random access memory; DRAM, SRAM): is the most common memory chip. will not remain if power goes off. must move data onto a disk if it is to be saved. ROM (read-only memory): information is stored permanently on a chip. contains startup information and other permanent data. PROM, EPROM, EEPROM PROM: Programmable once!. EPROM: Erasable (via ultraviolet light) and programmable EEPROM: Electrically Erasable and programmable
n data input lines n data output lines k address lines Rea d Writ e Mem ory Unit Block diagram of RAM RO M k address input lines n data output lines Block diagram of ROM
Instruction Cycle A program residing in the memory unit of the computer consists of a sequence of instructions. The program is executed in the computer by going through a cycle for each instruction. In the basic computer each instruction cycle consists of the following phases : 1. Fetch an instruction from memory 2. Decode the instruction 3. Execute the instruction
Input Devices Computers accept information from outside world using its input devices. Keyboard Mouse Touch screen Joystick Graphics tablet Track ball Microphone Video camera …...
Output Devices The information on the computer are sent to the outside world using output devices. Monitor Printer Speakers Other instruments/devices...
image is stored in video memory—VRAM. monitor size is measured diagonally across screen. images are made up of dots called pixels. color depth is the amount of information per pixel. the number of pixels affects resolution of the monitor. Screen Output Main Types: CRT LCD (Liquid Crystal Display)
Secondary Storage Peripherals with both input and output functions. This form of storage is semi-permanent. Examples include: Magnetic tape (sequential access) Magnetic disks (random access) HD: IDE, SCSI Floppy disks Optical disks (CD-ROM)