computer hardware computers and components. basic computer system main memory alucntl..... bus...
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Computer Hardware
Computers and components
Basic Computer System
MAIN MEMORY
ALU CNTL.....
BUS
CONTROLLER
Processor
I/O moduleInterconnections
BUS
ATTACHEDDEVICE
ComputerComponents
CPU Cycle
Start FETCH EXECUTE Halt
Increment Program Counter
FETCH EXECUTE
Execution Cycle
Instruction SetsComplex (CISC) or Reduced (RISC)
ALUCNTL
.....
ROM
INSTRUCTIONS
Measuring Processing Power
Clock SpeedInstruction SpeedWord Length and Bus WidthSpeed of ArithmeticInstruction SetPipelining
Primary Storage
Volatile DRAM SRAM Cache
Nonvolatile ROM
Kilobytes KB 1,000 BText document
Megabytes MB 1,000,KBImages
Gigabytes GB 1,000 MBHard disk drives
Terabytes TB TrillionsData warehouse files
Measuring Storage (bytes)
Attached I/O Devices
Secondary Storage DASD Tape Removable
Electronic Storage
Optical (etc.) devices
Communication Devices Modems and
Codecs LAN’s, Backbones
and WAN’s Routers and
other node devices
Secondary Storage Devices
Fixed Mediahard disksRAID
Removable Mediadiskettelaser-servo
diskettecartridge diskstapeCD-ROMflash memory
Attached Devices
Hardware: device itself such as a disk or video display device.
Electronics: controller that communicates with the device
Software: device driver that is loaded into the computer operating system
Local and Peripheral
Bus
Data Transfer:
MAIN MEMORY
BUFFER
CPU
T AAD
CONTROLLER
DASD
CPUCPUCPUCPU
CHANNEL
I/O Controller (DASD)
PROCESSOR REGISTER
REGISTER
REGISTER
BUFFER
Direct Access Storage Device (DASD)
DASD Structure
Read-Write Heads
Cylinder/Track/Block
Block (Sector)Track
Cylinder
Disk Organization
Data Storage
FAT (File Access Tables), Directories and Catalogs
Update and DeleteFragmentation and reorganizationBlocks, Headers and Interblock Gaps
Hardware II
General Purpose Computing
Software primacyApplications are controlled by changing the instructions run by the computer, rather than by changing the hardware
ASIC’s and FirmwareAny program that can be written in software can also be burned onto a chip as a family of circuits
Computer Classifications
Size mainframe midrange microcompute
r
Function legacy
mainframe server router client
Mainframe (Legacy)
Tuned for transaction processing
Has channels to support very large numbers of attached devices
Runs a mainframe operating system
Tend to support legacy software
Client/Server Architectures
SERVER PROCESSING
CLIENT PROCESSING
CENTRALIZED STAND-ALONE
FAT SERVER FAT CLIENT
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
ClientMay do some or all
of the processingRequests services
from the network
ServerContains data and
may contain programs
Server downloads information (applications or data) to the client for operation
Client
Use relatively inexpensive computer chips (Intel or Motorola)
Have a single processorOptimized for user
convenienceSingle userLimited numbers of
attached devices
Server
Use inexpensive CPU chips
Designed with redundant components
Have large internal memory capacity
May not need very fast CPU capability
Three Tier Client/Server
Any time Any place Any way
Router
Used to segment networks and prepare message packets for transmission
Special purpose operating system to read and forward message packets
May support firewall functionsSupport special purpose CPU chips
and optimized network sysems
Routers
Input Buffer
Proces- sor
Output Buffer
From A From B
To C To D
Table ofAddresses
Input Buffer
Input BufferOutput Buffer
Central ArchitectureClient/ServerWeb Access