Notes from Class Book Flashcards
Why is FDE cycle used
Cycle carried out to process data
What happens in the Fetch stage and what registers are involved
Fetches data from RAM and stores it in registers
PC, MAR, MDR
What happens in the Decode stage and what registers are involved
CPU Decodes and gets ready for next step
CIR
What happens in the Execute stage and what registers are involved
Instruction is carried out
ALU, ACC
What makes up the CPU
ALU, CU and Registers
What is clock speed
Instructions carried out per second. It can be increased, overclocking
What is pipelining
Where the output of one stage is the input of the next
Why is pipelining used
To speed up tasks
What is instruction pipelining
As one instruction is executed the next can be decoded and the next fetched, queueing them up and decreasing processing time.
What is are the limitations of pipelining
If it fails and fetches the wrong instruction them whole pipeline must be flushed
What are the 5 registers (in order of use)
PC
MAR
MDR
CIR
ALU
ACC
What does the PC do
Points to the address of the next instruction to be executed
What does the MAR do
Holds address of instruction in memory
What happens after MAR is used in FDE cycle
Address travels to RAM and data is returned by data bus
What does the MDR do
Stores data after it has been fetched from RAM
What happens after MDR is used FDE cycle
CU decodes instruction
What does the CIR do
Stores decoded instruction
What does ALU do
Performs arithmetic or logic calculations
What does ACC do
Stores result of calculations in ALU
What are buses and what are the 3 types
Metal tracks on the motherboard
- Address
- Data
- Control
What is a register
Small, temporary, super fast memory
What happens when you open a program
Data and instructions are loaded into RAM
What does the CU do
Decodes instructions, controls flow of data
What is a feature of both the data and control bus
2 directional (CPU <-> Memory)
What does the control bus do
Responsible for communicating control signals
What is a feature of the address bus
One directional (CPU –> Memory)
What affects performance of CPU
- Clock Speed (Hz)
- Cores
- Cache Size
- Heat
- Width of address bus
- Parallel Processing
What is clock speed determined by
Vibrations of a quartz crystal
What is the speed of the FDE cycle determined by
CPUs clock chip
Name the 4 types of primary storage
Cache, RAM, ROM, registers
Name 2 types of secondary storage
Hard disk, Flash drive
How does width of address bus affect performance of CPU
If the width is larger then more memory locations can be addressed
What is the Operand
The data itself
What is a drawback of parallel/concurrent processing
Some instructions are not compatible with parallel processing
What is the stored program concept
Program must be loaded into main memory to be executed by the processor - instructions are fetched one at a time
What is Von Neumann Architecture and name a limitation
Shared memory for programs + data instructions + data, both share a bus.
Limitation - Bottlenecking
What is bottlenecking
Component that limits the potential of other hardware due to the differences in maximum capabilities of the 2 components
What is Harvard Architecture and name a limitation
Separate memories with separate buses. Programs and data don’t have to compete for same bus
Limitation - Cost (very expensive)
When would Harvard be used over Von Neumann
When speed is more important than cost, if the system is a risk to life, normally in specialist embedded systems
Advantages of Von Neumann
Simplifies design of control unit
Cheaper
Data from memory and devices accessed in same way
Can processors use both architectures
Yes, In desktop computers Cache uses Harvard and RAM uses Von Neumann
What is CISC
Complex Instruction Set Computer
What is RISC
Reduced Instruction Set Computer
Features of CISC
- Quicker to code programs
- Compiler has little work to do to translate high level language to machine code
- As code is short, less RAM needed to store instructions
Features of RISC
- Instruction set made up of a small number of fixed length instructions
- Hardware is simpler to build with fewer circuits needed for carrying out complex instructions
- Each instruction takes same amount of time so pipelining is possible
- RAM is now cheap so RISCs use of RAM and software allows better performance processors at less cost
What is a GPU
Graphics Processing Unit, uses 1000s of small efficient cores.
Used to accelerate scientific, engineering and other applications
What is a Co-Processor
Uses an extra, more powerful core
Name 3 Manual Input devices
Keyboard
Microphone
Sensors
Name 3 Output devices
Printer
Projector
Speakers
Name 3 types of Sensor
Infrared
Light
Pressure
What are the 2 types of barcodes
- UPC-A Retail and Warehousing (digits only)
- Code 128 Transport and Shipment Tracking (Letters and numbers)
What is a Sensor
Hardware device that can take measurement of physical properties
What is Monitoring
Report Values
What is Control
Can change value of next input. The output can alter how the process operates
Name 4 types of Printer
- Inkjet
- Laser
- Dot Matrix
- 3D
What does an Inkjet printer do
Most common printer. Printer is cheap, the ink is marked up.
What does a Laser printer do
Uses dry powdered ink called toner. Businesses use them almost exclusively. Fast, reliable, excellent quality.
What does a dot matrix printer do
Impact printer, similar to a typewriter. Noisy, Expensive, poor quality. Useful in damp environment.
What is an RFID
Radio Frequency ID card. Use a transponder and reciever.
What is an Actuator
Motors commonly used in conjunction with sensors to control a mechanism.
