Systems Architecture Flashcards
What is a computer?
A computer is a machine that processes data
What is the purpose of a computer?
The purpose of a computer is to take data, process it , then output it
What is a computer system?
A computer system consists of hardware and software that work together to process data (complete tasks)
Define hardware
Hardware is the physical things that make up your computer system, like the CPU, motherboard, monitor and printer
Define software
Software is the programs or applications that a computer system runs
Example: an operating system, a word processor or video game
What are embedded systems?
Embedded systems are computers built into other devices, like dishwashers, microwaves and TVs. They are usually dedicated to one purpose
What are embedded systems often used as?
Embedded systems are often used as control systems- they monitor and control machinery in order to reach a desired result
Define embedded system
Embedded systems are computers inside a larger system
What does CPU stand for?
Central Processing Unit
What are the three main parts of the CPU?
The control unit (CU)
The arithmetic logic unit (ALU)
The cache
What is Von Neumann architecture?
The Von Neumann architecture describes a system where the cpu runs programs stored in memory. Programs consist of instructions and data which are stored in memory addresses.
What is the purpose of the program counter (PC)?
Program counter holds the memory address of the instructions for each cycle
Holds the address of the next instruction to be executed in memory
What is the purpose of the accumulator?
The accumulator stores intermediate results of calculations in the alu.
What is the purpose of the MAR?
The memory address register holds any memory address about to be used by the CPU. The address might point to data or a CPU instruction.
What is the purpose of the MDR?
The memory data register holds the actual data or instruction. This may have been fetched from memory or be waiting to be written to memory
What is the purpose of memory?
The memory holds the program instructions and the program data.
What happens in the fetch stage?
Copy memory address from the program counter to the MAR
Copy the instruction stored in the MAR address to the MDR
Increment the program counter to point to the next instruction ready for the next cycle
Gets data from RAM then brings it back to the cpu
What’s happens in the decode stage?
The instruction in the MDR is decoded by the CU. The CU may then prepare for the next step
What happens in the execute stage?
The instruction is performed.
What is the purpose of the cpu?
To process instructions by following the fetch, decode and execute cycle
What is the cache?
Provides fast access to regularly used instructions and data
What are the names of the registers?
Accumulator
Memory address register
Program counter
Memory data register
What are registers?
Tiny, incredibly fast pieces of onboard memory inside the cpu. All have a function specific to it.
What does Von Neumann consist of?
Control unit
Arithmetic and logic unit
Memory unit
Inputs and outputs
What are the factors that affect the CPU’s performance?
Clock speed
Cache size
Number of cores
How does the clock speed affect the cpu?
Number of the fetch, decode and execute cycle per second
How does cache size affect the CPU’s performance?
It quickly gets items from the cache rather than ram
How does number of cores affect the CPU’s performance?
Doubling the number of cores doesn’t double the overall speed
What are some common examples of embedded systems?
Traffic lights
Hospital equipment
Factory equipment
Domestic appliances
Engine management systems
What are some typical properties of embedded systems?
Low power consumption
Small size
Low cost per unit
Rugged operating ranges
What are the three types of storage?
Primary
Secondary
Tertiary
Define primary storage
ROM, RAM, registers and cache
Examples of secondary storage
Operating system
Programs and data are held when not in use
What does primary storage do?
Holds the data and instructions which are directly accessed by the CPU needs access to while a computer is running
Define RAM
Holds the operating system, programs and data that are in use by the CPU when the computer is running
What are some properties of ram?
Volatile
Temporary storage
Read and write
Large in comparison to ROM
Define ROM
Holds a the first instruction for when the computer is first turned on known as the bootstrap
What are some properties of ROM?
Non volatile
Permanent storage
Read only
Small in comparison to RAM
Why is virtual memory needed?
Virtual memory is needed when there is not enough physical ram to store the open programs.
Where is virtual memory held?
On the hard disk
What is secondary storage needed for?
Storing the programs and data whilst the power is turned off
It is a semi permanent storage of data that can change
The backup of data files
The archive of data files
What is the typical amount blu ray can store?
25GB per layer
What is the typical amount HD-DVD can store?
15GB per layer
Give examples of optical storage
Blu-ray, DVD R/RW, CD R/RW
Give examples of magnetic storage
Hard disk drive
Tape
Give examples of solid state
SSD, memory sticks, flash memory cards
What are some positives of optical storage?
Cheap
Light weight
Portable
What are some negatives of optical storage?
Slow access times
Prone to scratches
What are some positives of magnetic storage?
Cheap
Large capacity
What are some negatives of magnetic storage?
Fragile
Slow access times
What are some positives of solid state storage?
Durable
Fast access times
What are some negatives of solid state storage?
Cost
Limited read/ write
What factors do you need to consider when choosing a storage device?
Capacity
Speed
Portability
Durability
Cost
Reliability
What are the key characteristics of Von Neumann at architecture?
Central processing unit
Single control unit
Arithmetic logic unit
Onboard cache
Internal clock
