slr1 - Structure and function of the CPU Flashcards
What is the role of the control unit
Controlling and coordinating the activities of the CPU
Managing the flow of data between the CPU and other devices
Accepting the next instruction
Decoding instructions
Storing the resulting data back in memory
Which register Accepts the next instruction and decodes it
Control unit
What is stored in the program counter
The address of the next instruction in memory that the processor needs to execute
At the start of every fetch decode execute cycle where is the address in the PC copied to
The Memory Address Register
What is stored in the MAR
The address of the memory location data or instructions are to be read from or written to memory
Which register sends addresses to memory
MAR
Which bus only transfers data in one direction
Address
What is the role of the address bus
Transmits memory addresses from the processor to other parts of the system
What is stored in the MDR
Data which is read from or written to memory
What can the MDR also be called
“Memory Buffer Register” or “the gateway to the processor”
Where must all data going to and coming from memory pass through
The Memory Data Register
Which bus is responsible for transferring data to and from memory
Data Bus
Name the three buses
Control
Address
Data
What is held in the CIR
The current instruction being executed
If the data stored in the MDR is an instruction where is it copied to
The CIR
What is stored in an instruction
Opcode and Operand
What is opcode
The instruction being executed
What is the Operand
Which address in memory to execute it on
What is the role of the ALU
Performs arithmetic and logical operations on data
What are the 3 types of operation
Arithmetic
Bitwise
Boolean logic
what are bitwise operations
Operations that manipulate the individual bits of binary data
What is stored in the accumulator
The result of calculations carried out by the ALU
What is the role of general purpose registers
They temporarily store data within the CPU
What is the role of the control bus
Sends command and control signals to and from every component of the computer
What is carried by the data bus
The actual 1s and 0s that make up the information being transmitted around the CPU
What is the role of the decode unit
Prepares the execution of an instruction by looking up the binary operation code
What is the stored in the status register
Information about the status of the CPU
What is the role of the clock
Synchronises components by generating pulses at a fixed rate
What are the 3 main factors affecting the speed of a CPU
Clock speed
Cache size
Number of cores
How does clock speed affect the speed of a processor
higher clock speed means more FDE cycles per second
Why does cache size affect processor speed
A larger cache means that the cpu can have faster access to more instructions
What is cache
Small memory located on or near the CPU that temporarily stores data and instructions for faster access
Why is cache better than main memory
Cache is faster to access
describe a core
A complete copy of a CPU that contains all of the necessary registers
Why does the number of cores affect performance
CPUs with more cores have more power to run multiple programs at the same time
Why does doubling the number of cores not double the performance of a CPU
CPU cores have to communicate with each other
Many programs aren’t designed to use multiple cores
Describe the difference between a CMP and a CPU
A CMP houses multiple CPU cores
What does CMP stand for
Chip Multiprocessor
Describe the Von Neumann architecture
Shared memory for instructions and data
Instructions and data are stored in the same format
Each processor follows a liner fetch decode and execute cycle
One instruction at a time
Registers are used for fast access to instructions and data
Describe the Harvard architecture
Instructions and data are stored in separate memory units
Each of which has its own bus
Reading and writing can be done at the same time as fetching an instruction
Used by RISC processors
How do contemporary architectures differ from older architectures
They can make use of SIMD and MIMD
Describe SIMD
Where the processor uses parallel processing to carry out a single instruction on multiple items of data at the same time
Describe MIMD
Another version of parallel processing where multiple instructions are carried out on different data items across multiple cores
What is distributed computing
Where multiple computers on a shared network each take on part of a larger problem
What is a register
Small memory units that operate at a very high speed
What are the 6 instruction that can be sent down buses
Request
Grant
Memory write
Memory read
Interrupt request
Clock
