Unit 1 Components of a Computer Flashcards
What are the components of a CPU? (4)
- Control Unit
- Buses
- ALU
- Dedicated Registers
What is the Control Unit?
Part of the processor that coordinates the activity of all other components
How many lines does a Bus normally consist of?
8, 16, 32, 64
What is a Bus?
A series of connectors that transfer signals between components
What are the Control Signals? (5)
- Memory Read
- Memory Write
- Bus Request
- Bus Grant
- Clock
What does Control Signal: Memory Read do?
Causes data from the addressed location in RAM to be placed on the data bus
What does Control Signal: Memory Write do?
Causes data on the data bus to be written into the addressed location in RAM
What does Control Signal: Bus Request do?
Indicates that a device is requesting use of the data bus
What does Control Signal: Bus Grant do?
Indicates that the CPU has granted access to the data bus
What does Control Signal: Clock do?
Synchronizes operations
What are the Logical Operations of the ALU? (4)
- AND
- OR
- NOT
- XOR
What are the Arithmetic Operations of the ALU? (4)
- Add
- Subtract
- Divide
- Multiply
What is the job of the ALU?
Performs arithmetic, logical and shift operations on data
What is the job of the Accumulator?
Stores the results of the ALU
What are the Dedicated Registers? (5)
- Program Counter (PC)-
- Current Instructions Register (CIR)
- Memory Address Register (MAR)
- Memory Data Register (MDR)
- Accumulator
What does the Program Counter do?
Holds the memory address of the next instruction to be executed
What does the Current Instruction Register do?
Holds the current instruction (which is split into opcode and operand)
What does the Memory Address Register do?
Holds the address in memory where the processor is required to fetch or store data from or to
What does the Memory Data Register do?
Temporarily holds data moving between the processor and main memory
What does the Processor do?
Carries out instructions from programs stored in memory
What is the Fetch section of the FDE Cycle? (4)
- The address of the next instruction is copied from the PC to the Memory Address Register
- The instruction held at that address is copied to the Memory Data Register
- Simultaneously, the contents of the Program Counter (PC) are incremented
- The contents of the MDR are copied to the current Instruction Register
What is the Decode section of the FDE Cycle? (3)
- The instruction held in the CIR is decoded
- It is split into operand and opcode to determine the type of instruction it is
- Additional data, if required, is fetched from memory and passed to the accumulator
What is the Execute section of the FDE Cycle?
The instruction is executed and the result held in accumulator or stored in memory
What is a usual Word Length?
8, 16, 32, 64
Is the Data Bus Bi-Directional?
Yes
What factors affect Processor Performance? (3)
- Clock Speed
- Number of Cores
- Amount of Cache
What is the system Clock?
A series of regular ON/OFF signals are used to synchronize the operations of the processor components
What is Parallel Processing?
Using several processor cores working at the same time is known as parallel or concurrent processing
What is Cache?
Cache is a small amount of superfast (but expensive) memory that stores data and instructions that have recently been used by the processor
What is Pipelining?
Improves performance by overlapping stages in the FDE cycle or by breaking down the stages in an arithmetic instructions
What happens in Von Neumann Architecture?
Instructions and data are stored in a common main memory and transferred using a single shared bus
What happens in Harvard Architecture?
Data and instructions are separated into separate memories using different
What is an advantage of using Harvard Architecture?
Program instructions and data are no longer competing for the same bus
Where is Harvard Architecture used?
With specialist embedded systems and digital signal processing (DSP), where speed takes priority over the complexities of design
What are the advantages of Von Neumann Architecture?
- Cheaper
- Simplifies the design on the CU
- Data from memory and from devices are accessed the same way
How is Von Neumann and Harvard Architecture used in Desktop Computers?
There is one main memory for holding both data and instructions, but cache memory is divided into an instruction cache and a data cache so data and instructions are retrieved using Harvard architecture
What is CISC?
Complex Instruction Set Computers
A large instruction set is used to accomplish tasks in as few lines of assembly language as possible
What is RISC?
Reduced Instruction Set Computers
A minimum number of very simple instructions, each taking one clock cycle, are used to accomplish all the required operations in multiple general purpose registers
What are the advantages of CISC? (3)
- Quicker to code
- The compiler has less work to do
- Less RAM is used for storing the code
What are the advantages of RISC? (3)
- Hardware is simpler because there are less complex instruction
- Each instruction takes the same amount of time so pipelining is possible
- Cheaper
What do Multi-Core Processors do?
Distribute workload across multiple processor cores, thus achieving significantly higher performance by performing several tasks in parallel
What is a disadvantage of Parallel Processing?
The software has to be written to take advantage of multiple cores
What is a Co-Processor?
An extra processor used to supplement the functions of the primary processor
What is a GPU?
Graphics Processing Unit
A specialized electronic circuit which is very efficient at manipulating computer graphics and image processing
What are 2 common types of Barcoding?
Universal Product Code version A (UPC-A), Code 128
What is UPC-A used for?
Retail and warehousing
What is Code 128 used for?
Transport and shipment tracking
What is the main difference between UPC-A and Code 128?
Code 128 can represent letters and numbers whilst UPC-A can only represent numeric digits
What are the properties of an Inkjet Printer? (3)
- Most common
- Sold cheap
- Ink cartridges are expensive
What are the properties of a Laser Printer? (5)
- Use dry powder
- Colour or multi chrome
- Used for businesses
- Fast and reliable
- Excellent print quality
What are RFID?
Radio Frequency ID
Input/output devices that use a transponder and a receiver
What are some uses of RFID tags?
Shipment tracking, Banking and potential Barcode replacements
What is an Actuator?
Motors that are commonly used in conjunction with sensors to control a mechanism
What is an LCD monitor?
Liquid Crystal Display
Contain groups of red, green and blue diodes to form each pixel. Require backlighting
Why is using LEDs in monitors better than CCFL? (6)
- Very bright very quickly
- Image is sharper with more realistic/vivid colours
- Brighter light
- Thinner
- Last almost indefinitely
- Consume less power
What are advantages of OLED screens? (3)
- No need for backlighting
- Less heat
- Require less power
What are Multimedia Light Projectors?
Compact, high-resolution, full-colour projectors that can project text, images, video and audio content
What are the types of Memory? (2)
RAM, ROM
What are the features of RAM? (3)
- Read and write
- Volatile
- Stores OS, current programs and data
What are the features of ROM? (3)
- Read only
- Not volatile
- Stores bootstrap
What is Virtual Memory?
Virtual memory is part of the hard drive used as an extension to RAM
What is Primary Storage?
Volatile and usually refers to RAM
What is Secondary Storage?
Non-volatile storage
What are the features of a Hard Disk? (3)
- High capacity
- Relatively cheap storage per TB
- Fast read and write speeds
What are the features of Solid State? (6)
- Durable
- Less capacity than Hard Disk
- Faster than Hard Disk
- More portable
- Consumes less power
- More expensive than Hard Disk
What are the features of a USB? (4)
- Can store up to 128GB
- Cheap
- Can be password protected
- Useful for transferring data between computers
What are the 3 CD Formats?
CD-ROM, CD-R, CD-RW
What is CD-ROM used for?
Software distribution
What is CD-R used for?
Copying files or documents so they can be easily stored offline
What is CD-RW used for?
Short- or medium-term backup, or transferring files from one computer to another
What are DVD and Blueray used for?
Storing feature-length films
