CPU arch Flashcards
Computer hardware consists of……
Central Processing Unit (CPU)
Sound Card
Motherboard
Graphics Processing Unit (GPU)
Input & Output devices
Storage units (primary & secondary)
Computer arch designs
Von Neumann model
Harvard model
What does Harvard arch have separate memory for?
How is it different from Von Neumann arch?(2)
Harvard architecture has separate memory space for data and instruction.
Harvard differs from Von Neumann architecture which employs a single bus to both fetch instructions from memory and transfer data from one part of a computer to another.
Both the concepts are similar except the way they access memory locations
Idea behind Harvard arch?
The idea behind the Harvard architecture is to split the memory into two parts:
one for data
one for programs
What is it based on and what does it do?
Based on the original Harvard Mark I (1944) relay based computer which employed a system that would allow both data and transfers and instruction fetches to be performed at the same time.
Harvard model
…………………………………ALU
Instruction mem<—ControlUnit—>Data mem
………………………………… I/O
Vonneumann model-Who created it?Why?
What did he work on?
What are the components?
-Renowned mathematician and physicist John Von Neumann in 1945.
-Able to store instructions in the memory along with the data on which the instructions operate
-Harvard Mark I at IBM
-central processing unit (CPU),memory unit, input/output (I/O) interfaces
3 main components CPU
CPU heart of computer system 3 main components:
the Arithmetic and Logic Unit (ALU)
the control unit (CU)
Registers
-Accumulator (ACC)
-Program Counter (PC)
-Instruction Register (IR)
-Memory Address Register (MAR)
-Memory Data Register (MDR)
What do they do?
ALU
CU
Registers
Mem unit
I/O interface
*The ALU is responsible - carrying out all arithmetic and logic operations on data.
*The control unit (CU) determines - order of flow of instructions - need executed -> programs -> issuing control signals -> hardware.
*The registers -> temporary storage locations store addresses of the instructions - need executed.
*The memory unit = RAM, which- main memory used to store program data + instructions.
*The I/O interface allows users - communicate with outside world : storage devices.
Buses-What do they do?What are they?
What does the system bus control?
Buses transfer the data + instruction locations:
The System bus:
Address bus
Data bus
Control bus
The system bus controls the flow of data through the network
VNM vs Harvard
VNM- Theoretical design based->stored program computer concept.
Same memory for data and instructions
Processor-2 clock cycles-execute instruction.
Simpler CU design
Data transfer+instruction fetches X perform same time
Used in personal computers+workstations+laptops
Havard - Modern design - Havard Mark 1
Seperate memory address- data+instructions.
Processor-1clock cycle-execute instruction
More complicated design -2 separate buses
Data transfer+instructions fetches peform same time
Used - microprocessors
CPU
Computing equivalent of the human brain
main component -> computer, processing all the data and instructions
CPU components
CU
ALU
Internal mem
Registers
Buses
CU
Supervises FDE cycle
Sends + receives signals from all parts of the computer
Ensures processes are completed in the correct order
ALU
Processes + manipulates data
Performs simple calculations
Carries out logical operations
Internal mem
Known - cache memory (level 1)
Fast access temporary storage on the CPU
Data is moved from the cache to internal memory when not being used
Registers
Current Instruction Register (CIR)
-Stores the instruction that is currently being used by the CPU
Program Counter (PC)
-Stores the memory location of the next required instruction
Accumulator (ACC)
-Stores the results of the calculations made by the ALU
Memory Address Register (MAR)
-Stores the memory address location where data is currently being read/written
Memory Data Register (MDR)
-Stores the data currently being read/written
Buses
->printed circuits -> motherboard - connect components: I/O devices to the CPU + other parts of a computer:
Address Bus–Sends info about where data needs to go -> sending an address to the memory. Only sends data in 1 direction
Data Bus–Sends data to/from memory. Data flow either direction along - data bus
Control Bus–Carries commands from CPU and returns status signals from the device currently in use
FDE cycle
-The processor checks program counter-which instruction to run next.
-The program counter gives address value-> memory of where next instruction is.
-The processor fetches instruction value-> memory location
-Once instruction fetched needs- decoded+executed.
-The control unit checks instruction-> instruction register. Instruction - decoded to determine action - needs -carried out
-The action being executed -depended-> action being carried out
-Once- complete, processor goes back-program counter find next instruction.
-Cycle rep until program completed.
