Machine-level architecture

  • Created by: lily_mate
  • Created on: 18-01-17 13:31
Address bus
Single-directional - sends memory addresses (locations) to CPU from main memory
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Boolean algebra
Arithmetic performed on binary variables that can be either true (1) or false (0) - provides boolean logic rules
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Wires between computer hardware on which data is transferredd
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System bus
Data bus, address bus and control bus
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Clock speed (clock rate)
Speed at which a processor executes instructions, measured in Hertz
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Control bus
Bi-directional - sends control signals between components (e.g. clock timings and interrupt requests)
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Data bus
Bi-directional - transports data and instructions between components
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EEPROM (acronym)
Electronically Erasable Programmable Read-Only Memory
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EEPROM (definition)
User-modifiable read-only memory, can be edited by using higher than normal voltage
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EEPROM (example)
Flash memory
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Instruction set
Complete set of machine code instructions that a CPU can understand
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Logic gate
Performs basic logic functions, fundamental to digital circuits
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Machine code
Programming language of binary/hexadecimal instructions that a computer can respond to directly
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Main memory
Computer can only manipulate data in main memory - data must be copied from secondary storage to main memory to be interacted with by CPU
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Main memory (another name)
Primary storage
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Moore's law
Number of transistors per square inch on integrated circuits doubles every year since their invention
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Op code
Part of machine instruction that specifies operation to be performed
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Part of machine instruction that specifies data to be operated on
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CPU (acronym)
Central processing unit
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CPU (definition)
Handles and executes all instructions received from hardware and software on a computer
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RAM (acronym)
Random access memory
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RAM (definition)
Memory which can be accessed randomly (any byte can be accessed regardless of preceding byte). Faster than accessing data on CD or hard drive (sequential). Stores data and instructions in regard to programs that are being executed.
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RAM and ROM are types of...
Main memory
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ROM (acronym)
Read-only memory
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ROM (definition)
Memory with prerecorded data, can only be read once written to
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Data lost when power lost - RAM
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Data retained even when power lost - ROM
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System clock
Oscillating quartz crystal, gives cycles per second
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Three-box model
Expresses transfer of data between the processor, main memory and I/O devices via the system bus
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Truth table
Breakdown of logic function by listing all possible values of it
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Harvard architecture
Separate data and instruction buses - transfers can be performed simultaneously on both buses
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von Neumann architecture
One bus used for data transfers and instruction fetches - they must be scheduled and cannot be performed at the same time
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Which is faster - RAM or ROM?
RAM - random bytes can be accessed, not sequential
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Input device examples
Mouse, keyboard, touchscreen
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Output device examples
Monitor, speaker, printer
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Effect of increasing number of wires on a bus
Larger word size
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Word size
Number of bits that a bus can send at once
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Arithmetic logic unit
Part of CPU that carries out arithmetic operations on instruction operands
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Program control unit
Directs operations in a computer's processor - lets components know how to respond to instructions
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Special, high-speed storage area in a CPU - all data must be represented in a register before it can be processed
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General-purpose register
Used to hold intermediate results while working through arithmetic or an algorithm
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Dedicated register
Designed to carry out a specific role
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Dedicated register (another name)
Special-purpose register
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SP (acronym)
Stack pointer
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PC (acronym)
Program counter
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SR (acronym)
Status register
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ACC (acronym)
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CIR (acronym)
Current instruction register
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MAR (acronym)
Memory address register
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MBR (acronym)
Memory buffer register
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Stack pointer
Stores the address of the last program request in a stack.
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Set of storage locations - most recently stored is first to be received
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Program counter
Contains the address (location) of the instruction being executed at the current time
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Status register
Contains information about the state of the processor
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Status register - examples of flags
Overflow, negative
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Short-term, intermediate storage of arithmetic and logic data
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Current instruction register
Holds the current instruction to be executed, having been fetched from memory
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Memory address register
Holds the location in memory (address) of the next piece of data or program to be fetched (or stored).
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Memory buffer register
Stores data being transferred to and from the immediate access store
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Issues of increasing clock speed (clock rate)
Everytime clock ticks, heat generated = overheating. Transistor has not been getting any faster.
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Ways to improve computer performance
More RAM, using a RAID to lower read/write speeds, defragmenting hard drive, replacing a drive with faster drive
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Unifying program files in the same location
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Memory registers involved in fetch-decode-execute cycle
MDR, MAR, PC, ACC, IR (instruction register)
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Getting an instruction or data from main memory into the CPU using the address bus
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CPU decodes instruction and prepares for the next step
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Instruction is carried out upon data (executed) and result is stored in another register
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How machine code is represented
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Barcode reader
Sensor detects reflected light and generates analogue signal that represents intensity of the signal - this is then converted to a digital signal
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Digital camera
Takes light and focuses it via the lens onto a sensor, converts to pixels on grid
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Laser printer
Laser beam scans back and forth, builds pattern of static electricity that attracts ink. Fuser unit bonds this ink (toner) to the paper
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RFID (acronym)
Radio Frequency Identification Tag
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Radio waves used to transmit data
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Hard disk
Uses magnetic storage to store and retrieve digital information - uses one or more rotating disks coated with magnetic material
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Optical disk
Written to and read using a laser beam. Low-power laser scanner reads binary by being reflected off reflective material on disk
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Solid state disk
Uses grid of electrical cells to send and receive data - finds empty space in a block. When enough pages in a block are marked as unused, the SSD will take the entire content of that block, commit it to memory, and erase the whole block.
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Hard disk cost
GOOD - low cost per gigabyte
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Optical disk cost
GOOD - low cost per disk
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Solid state cost
POOR - more expensive than hard disk and optical disk
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Hard disk capacity
GOOD - offers up to several terabytes per device
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Optical disk capacity
POOR - can only store up to a few gigabytes
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Solid state capacity
GOOD - offers up to several terabytes per device
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Hard disk durability
AVERAGE - magnetic tape can hold its data for up to thirty years in the correct environment
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Optical disk durability
LOW - susceptible to scratches and the disk can snap easily
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Solid state durability
HIGH - no moving parts so little risk of damage. Can be written to over and over. Decreases over time, however
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Hard disk speed
AVERAGE - data read / write is not as fast as flash technology, but does offer high speed data access
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Optical disk speed
AVERAGE - data read fast by a laser
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Solid state speed
HIGH - no arm to read/write, data stored in microchips
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Hard disk portability
POOR - contains mechanical moving parts
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Optical disk portability
GOOD - can be kept in a disk case, lightweight
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Solid state portability
AVERAGE - no moving parts, but not necessarily portable unless it is an external SSD
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Other cards in this set

Card 2


Arithmetic performed on binary variables that can be either true (1) or false (0) - provides boolean logic rules


Boolean algebra

Card 3


Wires between computer hardware on which data is transferredd


Preview of the back of card 3

Card 4


Data bus, address bus and control bus


Preview of the back of card 4

Card 5


Speed at which a processor executes instructions, measured in Hertz


Preview of the back of card 5
View more cards


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