Arch & ops Flashcards
Define computer architecture and give an example
Those attributes that have a direct impact in the logical execution of a program
* E.g. the design of a house - computer models
Define Computer Organisation and give an example
Refer to operational units and their interconnections that realise the architectural operation
* E.g. Building a house with bricks & technology
Define computer structure
Computer structure is the way in which the components of the computer work together
Define computer function
Computer function is the operation of each individual component as part of the structure
What are the 4 main functions of the computer
. Data processing
. Data storage
. Data movement
. Control
What are the 2 types of data storage?
Long term and short term
What does data movement involve ?
- Input/Output
- Peripheral
- Data communication
What does data processing refer to?
Data processing refers to storage control and processing
What does data control refer to?
Data control refers to control processing and storage
What does computer structure consist of ?
○ Central Processing Unit(CPU)
○ Main Memory
○ I/O
○ System Interconnection(Buses)
What is the CPU ?
The cpu is a top level component that is basically the brain of the computer
What does the CPU consist of ?
○ Control Unit - Controls the operation of the CPU and hence the computer
○ Arithmetic & Logic Unit(ALU) - Performs the computer’s data processing functions it does this by making use of binary numbers and gates
○ Registers - Provides storage internal to the CPU(better definition in session 13)
○ CPU interconnections - Some mechanism that provides for communication among the control unit, ALU, and registers.
What does the control unit consist of ?
○ Sequencing logic
○ Control Unit Registers and decoders
○ Control Memory
What does ISA stand for?
ISA stands for Instruction Set Architecture
What is ISA ?
- It’s a stored program concept meaning when you write a program it is stored in memory
- Data & instructions(sometimes referred to as programs) stored in main memory
Does the ALU use binary numbers and make use of gates ?
Yes
What are the 2 types of ‘words’ in computer architecture ?
Number words & instruction words
What are number words?
Number words is for storing data. Basically stores binary numbers
What are instruction words ?
- Instruction word is split into left & right
The left or right is split further into opcode and address
What is the difference between opcode and operand?
- Opcode is operations that correspond to numbers
. Operand is the thing affected by the opcode.
.E.g. MULTIPLY 101 opcode is Multiply and the operand is 101
Give some info on instruction and number words
- Instruction and number words are addressable they have 1000 locations and you refer to addresses to fetch the data
Why are there 2 different types of words ?
To save space
What are registers ?
Registers are fast small and expensive memory. They are used by the processor to store small amounts of data that are needed during processing, such as: the address of the next instruction to be executed.
What does MBR stand for?
Memory buffer register
What does the MBR do and where is it located ?
MBR stores words in memory. It sends and receives these words stored in memory to the I/O Unit. It is located in the ALU
What does MAR stand for and what does it do ?
Memory Address Register.
* The MAR specifies(shows) the address in memory of the word to be written from or read into the MBR.
What does IR stand for and what does it do?
Instruction Register(IR) - Contains the 8-bit opcode instruction being executed. It Decodes the instructions and sends signal to the ALU
What does IBR stand for and what does it do?
IBR (Instruction buffer register). It temporarily holds the right hand instruction from a word in memory.
What does PC stand for and what does it do ?
Program counter(PC) - Points to the next address to be executed
What does the Accumulator do?
Holds the results of arithmetic & logistic calculations
What does MQ stand for and what does it do ?
The MQ(Multiplier Quotient) deals with multiplication
What does I/O AR stand for?
input output address register
What does I/O BR stand for ?
input output buffer register
What happens during the fetch cycle?
We read the instruction from memory
○ During the fetch cycle, the opcode of the next instruction is loaded into the IR and the address portion is loaded into the MAR. This instruction may be taken from the IBR, or it can be obtained from memory by loading a word into the MBR, and then down to the IBR, IR, and MAR.
What happens during the execute cycle ?
The execute cycle is where we execute this part starts after the IR.
○ Once the opcode is in the IR, the execute cycle is performed. Control circuitry interprets the opcode and executes the instruction by sending out the appropriate control signals to cause data to be moved or an operation to be performed by the ALU.
What is Instruction set
Basically LMC make sure you practice
What are the 3 concepts in ISA ?
- Single read-write memory
- Addressable Memory
- Execution occurs in a sequential fashion from one instruction to the next unless modified. A good example of this modification is interrupts
What is the difference between hardwired and software ?
- Hardwire is a function or device that is physically built into the computer instead of programmed into the software. Hardwired functions cannot be removed from the computer and usually allow hardware to control the operation instead of software.
In software the Instruction codes are sent to the instruction Interpreter(II). It then sends a control signal to the ALU and retrieves the data.
Look at fetch execute question from week 14
Do IT NOW
What comes under interconnection structure ?
- Computer as a network of basic modules
- Paths for connecting the modules
- Structure depends on the exchanges
What type of transfers must interconnection support ?
Memory to Processor:The processor reads an instruction or a unit of data from memory.
Processor to Memory:The processor writes a unit of data to memory
I/O to Processor: The processor reads data from an I/O device via an I/O module.
Processor to I/O: The processor sends data to the I/O device.
I/O to or from Memory: I/O module is allowed to ex- change data directly with memory, without going through the processor, using direct memory access.
What comes under Computer Communication?
- Find the address
- Data communication is needed
- Reading and writing signals
What comes under Input/Output devices ?
- Read/write
- Control more than one external device (port - unique address)
- External data path(input/output) with an external device
- Interrupt signals
What comes under Processor?
- Reading instruction and data
- Write out data after processing
- Use control signals to control the overall operations