Computer Hardware Computers and components Basic Computer System
Computer Hardware Computers and components
Basic Computer System Processor ALU CNTL. . . BUS Interconnections I/O module CONTROLLER MAIN MEMORY BUS ATTACHED DEVICE
Computer Components
CPU Cycle Increment Program Counter Start FETCH EXECUTE Halt
Execution Cycle
Instruction Sets Complex (CISC) or Reduced (RISC) INSTRUCTIONS ROM CNTL ALU. . .
Measuring Processing Power z. Clock Speed z. Instruction Speed z. Word Length and Bus Width z. Speed of Arithmetic z. Instruction Set z. Pipelining
Primary Storage z. Volatile y. DRAM y. SRAM y. Cache z. Nonvolatile y. ROM
Measuring Storage (bytes) z. Kilobytes KB 1, 000 B Text document z. Megabytes MB 1, 000, KB Images z. Gigabytes GB 1, 000 MB Hard disk drives z. Terabytes TB Trillions Data warehouse files
Attached I/O Devices z Secondary Storage y. DASD y. Tape y. Removable Electronic Storage y. Optical (etc. ) devices z Communication Devices y. Modems and Codecs y. LAN’s, Backbones and WAN’s y. Routers and other node devices
Secondary Storage Devices Fixed Media hard disks RAID Removable Media diskette laser-servo diskette cartridge disks tape CD-ROM flash memory
Attached Devices z. Hardware: device itself such as a disk or video display device. z. Electronics: controller that communicates with the device z. Software: device driver that is loaded into the computer operating system
Local and Peripheral Bus
Data Transfer: MAIN MEMORY DBUFFER A T A CHANNEL CPU CONTROLLER DASD
I/O Controller (DASD) PROCESSOR REGISTER BUFFER
Direct Access Storage Device (DASD)
DASD Structure Read-Write Heads
Cylinder/Track/Block Track Block (Sector) Cylinder
Disk Organization
Data Storage z. FAT (File Access Tables), Directories and Catalogs z. Update and Delete z. Fragmentation and reorganization z. Blocks, Headers and Interblock Gaps
Hardware II
General Purpose Computing z. Software primacy Applications are controlled by changing the instructions run by the computer, rather than by changing the hardware z. ASIC’s and Firmware Any program that can be written in software can also be burned onto a chip as a family of circuits
Computer Classifications Size ymainframe ymidrange ymicrocomputer Function ylegacy mainframe yserver yrouter yclient
Mainframe (Legacy) z. Tuned for transaction processing z. Has channels to support very large numbers of attached devices z. Runs a mainframe operating system z. Tend to support legacy software
Client/Server Architectures FAT CLIENT FAT SERVER PROCESSING CLIENT PROCESSING CENTRALIZED STAND-ALONE
Client/Server Architecture An architecture in which the client (personal computer or workstation) is the requesting machine and the server is the supplying machine, both of which are connected via a network.
Client/Server Architecture z Client z May do some or all of the processing z Requests services from the network z Server z Contains data and may contain programs z Server downloads information (applications or data) to the client for operation
Client z. Use relatively inexpensive computer chips (Intel or Motorola) z. Have a single processor z. Optimized for user convenience z. Single user z. Limited numbers of attached devices
Server z. Use inexpensive CPU chips z. Designed with redundant components z. Have large internal memory capacity z. May not need very fast CPU capability
Three Tier Client/Server
Any time Any place Any way
Router z. Used to segment networks and prepare message packets for transmission z. Special purpose operating system to read and forward message packets z. May support firewall functions z. Support special purpose CPU chips and optimized network sysems
Routers From A From B Input Buffer Processor Output Buffer Table of Addresses To C To D
z. Central Architecture z. Client/Server z. Web Access
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