4.- Fundamentals of Computer Organisation and Architecture Flashcards
(12 cards)
What is a computer? What is it made up of?
A computer is an electronic/digital device/ that carries out a series of arithmetic and logical operations / upon a set of data
What is an I/O Contoller?
How does it act as a buffer?
An I/O controller** sits between the I/O device and the CPU. It allows for devices to connect to the computer/CPU
It translates what the processor sends out in a form that can be understood by the I/O device and* vice versa*
**
IT CAN ACT AS A BUFFER:
Inputs from I/O devices are classified as interrupts. The buffer signals to the CPU to continue with other instructions, so that the CPU is not left waiting unnecessarily on the I/O device (WHICH IS ESSENTIAL DUE TO DIFFERING OPERATING SPEEDS)
Why do we use I/O contollers?
Each device operates at different operating speeds with different sets of electronic signals
I/O contoller provides a SET OF ADDRESSABLE REGISTERS that the CPU can access to communicate with the I/O devices
A physical point provides connection for the peripheral
What is Main memory? What are the different types? What are their properties
Main memory is memory that is used to store programs and software which are currently being used/executed (for direct access by the CPU).
It is faster than secondary memory.
RAM - Random Access Memory
-Volatile - contents will be lost without power
- Stores data and instructions currently in use
ROM - Read Only Memory
- Stores data/information required for the boot cycle of the system. Cannot be appended easily, and it set at time of manufacturing. Non-volatile
What are busses?
A bus is a series of parallel wires that passes information/data between components of a computer system via the busses. Each bus transmits a single bit. More wires = more data passed per cycle.
Number of parallel wires = width = direct relationship to the number of bits that can be transmitted at once.
Explain early computer architecture and the von neeumann architecture (stored Program concept)
Early computers were originally built to complete one instruction/task. To change the task that a computer was required to complete would entail re-wiring and re-arranging internal components which took up time and monney
The Von Neumann architecture introduced the Stored Program Concept , where a memory unit, that can store both instructions and data, and can be retrieved* as and when needed*, prior to execution
What are the advantages of the von neumann architechture?
- When required, a new set of instructions can be loaded into memory
- The computer can take/complete different tasks to the ones it handled previously
- Instructions can be re-written during execution
What are the disadvantages of the Von-Neumann architecture?
- Only one bus is used to transmit data AND instructions
This can cause a delay or a bottleneck when the CPU has to wait for the next instruction/bit of data. This reduces performance.
How can the Von-Neumann bottleneck be solved?
The harvard architecture can be used!
- Similar design to the von neumann BUT Harvard allocates two seperate main memory components for data and instructions
- Each main memory component has its own set of busses! - Faster performance as a result
What are some common examples where harvard architecture is used?
- High-performance machines
- Embedded systems
- Digital signal processing
- Real-time data analysis
Extra benefit:
Reduces chance of dormant viruses becoming active. Viruses are often disguised as data. The Harvard architecture will** identify the virus as data, not an instruction, so it CANNOT BE EXECUTED!**
BUT MORE EXPENSIVE!!!
What are some other architecture design examples?
- Parallel processing (same instruction carried out on multiple pieces of data OR multiple instructions on multiple pieces by multiple cores)
- Distributed Computing - Multiple computers process 1 task (e.g.NASA)
What are the names of the 3 types of busses?
- Adress Bus - Carries memory addresses from the processor to other components e.g. main memory (unidirectional)
- Data bus - Carries data between the CPU, memory, and I/O devices (Bi-directional)
- Control Bus - Carries signals sent from the CU to other components of the CPU to tell them to complete tasks/actions, and the CU will request confirmation from each component that is has completed the task - sent via the bus also (BI-directional)
“Ensures that everything flows in the right direction to the right component at the right time”
