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1. Major Hardware Components of a Computer System Central Processing Unit
2. Central Processing Unit Arithmetic/Logic Unit (ALU): processes data arithmetically (addition, subtraction, multiplication, division) or logically (greater than, less than, equal to)
Control Unit: works with the operating system to move data between auxiliary storage and main memory; and between main memory and the ALU
Main Memory: contains both program instructions and the data that is required.
A single machine can have multiple CPUs to share processing tasks (co-processors, multiprocessing), but each CPU can execute only a single task.
3. Inside the System Unit Main component: motherboard
Circuit board that houses integrated circuits (microscopic elements wires, transistors, etc) required to make the digital pulse flow inside of the computer. Pulses flow from component to component via the bus
Some microcomputers contain a special local bus (VESA or PCI) which increase data transfer rates to the display and/or storage devices
4. Motherboard (cont.) Attachments to the motherboard include:
Main Memory: types of main memory include:
RAM - temporary (includes virtual memory storage). Include RAM cache
ROM - permanent
CMOS - semipermanent battery powered
Memory chips attach with either a DIP (dual inline pin - old PCs) or as a SIMM (single inline memory module) board
When add main memory, make sure add-on chips are compatible
Real time clock (current date and time)
Microprocessor or CPU (central processing unit)
Control Unit: traffic cop portion of the CPU
ALU: arithmetic logic unit processes all math and logical operations performed by the computer
5. Expansion slots/add on boards - allow cards that attach various peripheral devices to the motherboard
monitors, hard drive, internal fax/modem, network cards,etc
PCMCIA slots: special slots developed for laptops to attach devices and add on RAM
Expansion devices may provide an external port which you connect a cable to. Device ports will either be from an internal or external bay in the system unit.
Serial Port: transmits data one bit at a time (modem)
Parallel Port: transmits 8 bits simultaneously (printers, backup devices, etc.)
SCSI Port: allows several devices to be chained together and connected through a single SCSI (small computer system interface)
MIDI Port: musical instrument digital interface
6. Main Memory Random Access Memory (RAM): allows data and instructions to be accessed randomly from any memory location (address). Primary storage.
Volatile - lost when power is turned off
Read Only Memory (ROM): usually contains programs that help the computer system operate:
can only be read: cannot be written to or altered by the user (usually)
ROM is not volatile
7. Main Memory Data and instructions are stored as BITS (binary digits). Everything from our world is translated into a computer recognizable format called binary (zeros or ones)
The combination of binary digits represents our letters or numbers. One character represented is equal to a byte.
Memory capacity is measured in bytes. Todays most common measurement is megabytes
Kilo = 1,000 (KB) Thousand
Mega = 1,000,000 (MB) Million
Giga = 1,000,000,000 (GB) Billion
Bytes are composed using either the ASCII coding system (7 bits = character) or EBCDIC (8 bits = character)
8. Microprocessor Families Intel (IBM) and Motorola (Macintosh 68000) two main manufacturers
Microprocessors are families - upward increases in speed (early SX vs DX chips)
Increase in bus capacity indicates a new generation
9. The Boot Process When you turn your computer on, the following activities happen:
Power is sent to the internal fan and the motherboard
The boot program stored inside of ROM activates
The Power-On Self-Test (POST)runs and tests required system components
The operating system/environment is loaded
Configuration and customization routines are executed which set your computer environment
10. Input/Output Peripheral Devices Badge Reader
Cartridge & cassette drives
Digital tables & scanners
Keyboard, mouse, pens
Touch screen SASD & DASD drives
Page vs line or character printers
Impact vs nonimpact
11. StorageRequired because main memory is limited, expensive and volatile. Sequential Access Storage Devices (SASD): data is stored in sequential order. Retrieval is also sequential.
Storage media is magnetic tape.
Supports batch processing environment
Excellent form of backup
Direct Access Storage Devices (DASD): data can be stored and retrieved randomly.
Storage capacity is referred to as density. How tightly packed data is on the disk.
DASD is required for transaction processing.
Memory capacity is measured in bytes. Todays most common measurement is kilobytes, megabytes and gigabits.
12. Printer Considerations Dot matrix - low price & inexpensive to operate. Lower quality. Impact - can print carbon forms. Color option. Slow.
Ink jet - moderate price & better output. Color option. Nonimpact. Quieter.
Laserjet - more expensive. Faster. High quality. Nonimpact.
13. Display Considerations Screen size- diagonal measurement from corner to corner. Popular sizes are 14, 15 and 17
Dot pitch - measure of image clarity. The smaller the dot pitch, the crisper the image or resolution.
Video adapters/cards impact image resolution and display speed. Today, most monitors are Super VGA (1024 x 768)and use non-interlaced projection technology (flicker)
Laptop - liquid crystal display (LCD). Passive matrix vs active matrix screen (display method which impacts image quality). Active matrix is much better but more expensive and can have problems.
14. DASD Floppy Disk: removable DASD. Most common density is 1.44Mb.
Hard Disk: usually dont remove (but newer devices you can). Higher storage capacity than floppy disks. Faster access.
Winchester drive architecture is not removable.
Can be drives that have removable disk platters.
Optical disk: CD_ROM (read-only) Erasable optical disk is also available. WORM - write once, read many.
Flash memory: main memory on a card. Non volatile. PCMCIA card.
15. DASD cont. All data stored on DASD media is stored in pie-shaped sectors that determines how much data is moved into and out of main memory at a time.
Virtual storage: operating system uses hard disk drive as an extension of main memory.
Cache memory: operating system assumes that most data used by an application is accessed over and over again. Cache is a special area in main memory where such data is put instead of paging it back and forth to DASD.
16. DASD cont WORM: write-once, read many. (CD ROM). Also have rewriteable CD ROM.
Floptical Disk: optical storage capacities on floppy disk.
DVD: Digital video disk
Hierarchical Storage: use of many different types of DASD & SASD devices to achieve storage requirements.
17. Other considerations: Desktop vs Laptop - expansion slots and capability
Port replicators vs docking station
Pointing device. Track ball, touch pad, erase point.
Power management & battery considerations (hot swap)
Multimedia devices - sound cards, speakers and MPC standards
18. Common File Types Data Files: files of information created when people use various types of software
Executable Files: Types of systems files that are used by the computer to perform certain tasks. With some executable files (.exe., .com, .bat) you can initiate the processing while with others the computer initiates the process (.dll, .sys, .drv, etc.)
You and your AUTOEXEC.BAT file.
19. Anatomy of a Filename Rules for creating valid filenames (appropriate characters, length of names, etc.) depends on the operating system being used.
Components of a filename consist of: C:/foldername/filename.ext Drive Designation Folder/subdirectory
name File name from
you File extension
supplied by the
20. File Storage Logical Storage:
How you perceive that data is stored on an auxiliary storage media
No indication of fragmentation Physical Storage
How data actually resides on your auxiliary storage media
File Allocation Table (FAT)
Fragmentation is normal
21. Measurements of Computer Power Clock speed: electronic pulses used to synchronize processing. Faster clock speeds result in more operations in a give amount of time. Measured in megahertz (MHz).
Bus width: determines how much data can be transferred at any one time. 16 bit, 32 bit, 64 bit.
IBMs Microchannel (MCA) Architecture vs EISA (open architecture)
Word size: number of bits/bytes manipulated at once. Same as the bus width.
Other determinants include main memory capacity, MIPs.
This is not the same as throughput but it can affect throughput..