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Who designed the architecture used in the design of most modern computer systems?
List and describe the five components in vonNeumann's model.
- Input devices (keyboard, mouse, etc)
- Random Access Memory (stores data and programs)
- Output devices (screen, printer, etc)
- Secondary Storage (Disks, etc)
- Central Processing Unit (control unit coordinates CPU activity, Arithmetic/Logic Unit processes data)
Name and describe the eight parts of the CPU.
- 1) Code cache - storage for instructions for deciphering data
- 2) BusInterface unit - Information from RAM enters here, then is sent to separate storage units or cache
- 3) Arithmetic Logic Unit - Whole number cruncher
- 4) Data cache - Sends data from ALUs to BusInterface Unit, then back to RAM
- 5) Branch predictor unit - Decides which ALU can best handle specific data and divides the tasks
- 6) Instruction prefetch & Decoding Unit - Translates data into simple instructions for ALU to process
- 7) Floating Point Unit - Floating-point number cruncher
- 8) Instruction Register - Provides the ALUs with processing instructions from the data cache
Describe the simplified view of the CPU.
The RAM is connected by the Bus to the ALU, Registers (for storing data), and the control unit (that coordinates the operation of the computer).
Describe the four steps in the VonNeumann processing cycle.
- 1) Fetch the next instruction from main memory. (Main memory)
- 2) Decode instruction to determine what to do. (Control unit)
- 3) Execute the decoded instruction. (ALU)
- 4) Store the result in main memory. (Main memory)
- ...then the cycle continues
What is RAM?
RAM stands for random access memory. The user can 'randomly' access any part of memory (as long as the location of what's being accessed is known).
The binary values stored in dynamic RAM __________________ so that the charge doesn't dissipate causing the values to be lost.
must be refreshed thousands of times per second
What type of device actually holds the charge in RAM?
Cache mememory is fast but rather expensive, so it is used in smaller amounts than RAM in most machines. Describe how it is typically used.
Since static RAM is faster, it is used to store the information that was most recently accessed (like the current program being executed or data currently being used). If the information is not found in the static RAM, it will look in the dynamic RAM.
What type of memory circuitry is used for static RAM?
Both static and dynamic RAM lose their values when they lose power. An alternate form of data storage was developed so that memory could persist even without power. Name the type of storage and give an example.
Magnetic storage is non-electronic storage. An example of non-magnetic storage is a hard drive.
Describe how a hard drive functions?
- Hard drives contain several disk shaped platters. Each platter is divided into concentric circles called tracks. Each track is divided into wedges called sectors.
- The read-write head moves radially toward or away from the center of the platter until it reaches the right track. The disk spins around until the read-write head reaches the appropriate sector.
- The read-write head aligns the filaments in the hard drive either "N-S" or "E-W" to represent 0s and 1s.
Describe how optical memory works.
Data is written in tracks, and data is represented in binary as short pits and longer pits. When the data is read, a laser is projected where the data is recorded, and the device notes if the laser beam has been reflected or not.
What is Flash memory?
Flash Memory is Electrically Erasable Programmable Read-Only Memory (EEPROM). It retains data with no power. It works like fuses: to store a 0 leave the circuit alone; to store a 1 "blow" the circuit.
A keyboard is a type of __________ device.
How do keyboards work?
When a key is pressed, a plunger on the bottom of the key pushes down against a rubber dome, the center of which completes a circuit within the keyboard, signaling the CPU which key has been pressed.
A mouse is a type of ________ device.
How does a mouse work?
Optical mice use red LEDs or lasers to illuminate the surface beneath the mouse, and sensors detect the subtle changes that indicate how much and in what direction the mouse is being moved.
What does LCD stand for?
Liquid crystal display.
What type of device is an LCD?
How does an LCD work?
Light passes through a horizontal polarizer which converts the light into horizontal shafts. A thin film transistor applies charge to individual subpixel. A color filter provides red, green or blue color to the resulting light. Then a vertical polarizer allows light through in proportion to how much the beam is twisted. This controls the color intensity of the pixel.-
Name four types of touch screen displays?
- Resistive - conductive materials meet where touched, producing a locatable voltage
- Capacitive - there is voltage at each corner, touching the screen draws current from each corner. Measuring the ratio of the four currents determines the touch location.
- Infrared - A grid of infrared LEDs and photoreceptors exists on the screen. Touching the screen breaks beams that specify the x and y coordinates.
- Acoustic - Four ultrasonic devices are placed around the display. Touching the screen produces an distinct acoustic pattern that is compared to the known patterns to determine the touch location.