Computer Hardware

What Is a Computer A data processing machine operated automatically under the control of a list of instructions (called a program) stored in its main memory. A data processing machine operated automatically under the control of a list of instructions (called a program) stored in its main memory.

What Is a Computer

What Is a Computer System

History of the PC n IBM announced that it would use external sources for hardware and software components. –Intel would make the Microprocessor (e.g. Brains) –Microsoft would develop the operating system –called “Open Design”

History continued... n Original Mass Prod. Business PC was by IBM –2 floppy drives –a monochrome monitor –80cps dot matrix printer –software was a character based operating system –prices were approx.. $ –was an instant success… WHY????

History continued... n IBM reputation for mainframe computers ensured it would perform as promised. n The PC open designed allowed the user to add second party hardware via expansion cards. –expansion cards hold additional circuit boards and thus increase the functionality

History continues... –IBM made public the technical information to produce these expansion cards (or adapters) –3rd party vendors began making adapters to increase the sound, speed, and resolution of computers. n Open design was a mix blessing for IBM…. WHY????

Open Design n “+” Increased business at first. People could now customize the computer for their own need.. And use it for specific problems. n “-” eventually (1982) PC compatibles or CLONES began to appear on the market. –these compatibles were based on the same INTEL processor. same INTEL processor.

Open Design –Were less expensive than IBM. IBM charged a premium for their systems due to their reputation. –New systems offered superior performance than IBM. IBM was slow to introduce new changes to their PCs. –IBM went from 1980 (100% Market share) to 1998 (< 10%).

The Microprocessor n - Microprocessor (CPU - Central Processing Unit)- Computers high speed memory, logic, and control are on a single chip. –6 generations of Intel micro processors n 8088 (XT), (AT), 80386, 80486, Pentium (+MMX), Pentium Pro. n all are obsolete with the exception of high end Pentiums and Pentium Pros.

The Microprocessor n The speed of a microprocessor is dependent on 2 things… –the generation of the microprocessor –the clock speed n indicates how fast instructions are processed. n measured in MHz (millions of cycles per second)

The Microprocessor n Example: –A 200 MHz Pentium is faster than a 166 MHz Pentium. –but how much faster. –how much faster is a Pentium Pro 200 MHz compared to a Pentium 133 MHz.

ICOMP Index n To compare current Intel microprocessors (CPU) we use the ICOMP index. –performance index of Intel CPUs. –the higher the number, the faster the CPU. –allows you to purchase the fastest machine you can afford. n Lets take a look at the ICOMP index.

Primary Memory n Primary Memory (RAM)- A temporary storage area that holds data instructions, results, and passes information back and forth to the CPU. –the larger the memory the more sophisticated programs can run. –more programs can remain in memory at the same time. –the faster the system.

Primary Memory n Memory (Random Access Memory) –made up of individual storage locations, each of which holds one character (called a Byte) –A Byte is made up of 0’s and 1’s. Each 0 or 1 is called a Bit (Binary Digit). 8 Bits make a Byte. – = 193

Primary Memory n The amount of memory is measured by the # of bytes it can hold: –1 Kilobyte (KB) = 1,024 bytes –1 Megabyte (MB) = 1,048,576 bytes or 1000 (KB) n RAM memory is VOLATILE. It is lost as soon as you shut of the power. –therefore what….

Primary Memory n We need an permanent storage area. n This permanent memory is called secondary or auxiliary storage. –types ???

Auxiliary Storage n A permanent storage device that retains its contents when the power is turned off. –hard (fixed) Disk - remains permanently inside the system unit. (uses metal platters) –floppy disk - is portable and is made up of a plastic disk, enclosed in a hard plastic case.

Auxiliary Storage n Hard disk will hold more data than a floppy disk. n Hard disk space is measured in Gigabytes (1GB = 1000MB = 1 Billion Bytes) n Floppy Disk (3.5” Floppy) –high Density (1.44 MB) –double Density (720 KB)

Auxiliary Storage n CD-ROM - compact disk read only memory –you can read from the CD but can not write to it. –CD hold approx.. 650MB of data. n CD-Recordable –allows you to read and write to a CD.

CD-ROM and Recordables n Speeds of CD-ROMs and recordables are measured by –access Time: The average time to find a specific item. –transfer Rate: The amount of data that is read/second

CD-ROMs and Recordables n 1st CD-ROMs had speeds of 600 millisecond access time and transfer rates of 150 KB. n Speeds are now up to 32 times the original speed (32X).

The Local Bus n The Bus is –the circuitry on the motherboard (the main board that holds the microprocessor, memory, and adapter cards) that –provides a path for which data travels from one component to another.

The Local Bus n Today’s PCs have multiple local buses –each Bus is 32bits wide and travels as fast as the microprocessor. –each Bus is connected to a specific device and does not have to share it with other components. –PCI - A bus designed by Intel for the Pentium or Pentium Pro.

Printer n Printers –Dot Matrix n lots of noise n bad Print Quality –Inkjet n today’s entry level printer n quite and pretty good speed –Laser n top of the line n quality measured in PPM and DPI.

Modem n Connects you computer to the outside worlds n Modulate - Converts a digital signal into an analog one n Demodulate - Converts an analog signal to a digital one. n Modem = Modulate demodulate n Example

Modem n Speed is measured in BPS (Bits per second) n Standard speed today is 28,800 BPS (28.8 KBPS) to 33,600 BPS (33.6 KBPS) n Today the standard is a FAX/MODEM where you get the functions of a MODEM and a FAX machine on one card.

Sound Card n 2 Functions –play previous recorded sound (translates a digital file into sound) –to record new sound (translate sound into a digital file) n Need good speakers n Every sound card has at least 2 chips

Video n 2 major components –monitor –display Adapter (Video Card) n Monitor –pixels –dot pitch –vertical refresh rate

Monitor Quality n Pixels - (PICture ELementS) –the number of dots that make up a picture –measured by –# of dots across X # of dots down n 800 X 600 –in this example the max number of pixels that can be displayed on any monitor is 800 X 600 = 480,000

Monitor Quality n This formula (Pixels across X Pixels down) is called the resolution. n The bigger the monitor the larger the dots and the easier it is to see the image n The higher the resolution the sharper the image. n But…

Monitor Quality n What happens when... –small Monitor and High Resolution n 14” 1280 X 1024 (1,310,720) –large Monitor and Low Resolution n 20”640 X 480 (307,200) n Need a balance between resolution and monitor size.

Resolution and Monitor Size Min ResolutionPixels Screen Size 640 X 480 (VGA)307,20014” 800 X 600 (Super VGA)480,00015” 1024 X 768 (Extended VGA)782,46217” 1280 X ,310,72020”

Monitor Quality n Dot Pitch - –distance between adjacent Pixels n The smaller the dot pitch the crisper the image (good) the smaller the dot pitch the more grainy the image (bad). n Get a monitor with a dot pitch less than.28 mm.

Monitor Quality n Vertical refresh rate –how fast the screen is repainted (refreshed) from top to bottom n If it is too slow the screen will flicker. n Get 70MHz (70 cycles per second) or faster.

Display Adapter n Display (video) adapter - accepts info from the CPU and sends it to the monitor to display the image –get one with an accelerator chip. The video card will have its own processing chip. Freeing up the CPU to do other things. –the video card should also have its own memory (at least 1 MB).

Summary n History of computers n Microprocessors. n Primary and second memory. n The local bus. n Other hardware such as printer, modem, sound card, monitor display etc. n Next lecture on computer software.