Unit 1 Pg Online Flashcards
What is the fetch-execute cycle?
Processors operate in defined stages to carry out program instructions repeatedly.
What is the accumulator in a processor?
A general purpose register used to temporarily store results of calculations.
What does the Arithmetic-Logic Unit (ALU) do?
Performs arithmetic, logical, and shift operations on data.
List the arithmetic operations performed by the ALU.
- Add
- Subtract
- Multiply
- Divide
What logical operations does the ALU perform?
- AND
- OR
- NOT
- XOR
What are shift operations in the context of the ALU?
Move bits to the left or right within a register.
What does the control signal ‘Memory read’ do?
Causes data from the addressed location in RAM to be placed on the data bus.
What is the function of the control signal ‘Memory write’?
Causes data on the data bus to be written into the addressed location in RAM.
What does the control signal ‘Bus request’ indicate?
Indicates that a device is requesting use of the data bus.
What does the control signal ‘Bus grant’ signify?
Indicates that the CPU has granted access to the data bus.
What is the role of the clock in a processor?
Used to synchronize operations.
What is a bus in computer architecture?
A series of connectors that transfer signals between internal components.
How many lines do buses typically consist of?
8, 16, 32, or 64 lines.
What is the function of the Control Unit in a processor?
Coordinates the activity of all other components.
What are the main components of the Central Processing Unit (CPU)?
- Control Unit
- Buses
- Arithmetic-Logic Unit (ALU)
- Dedicated registers
What is the purpose of dedicated registers in a processor?
To hold various pieces of information required for executing instructions.
What does the Program Counter (PC) hold?
The memory address of the next instruction to be executed.
What is stored in the Current Instruction Register (CIR)?
The current instruction, split into opcode and operand.
What is the role of the Memory Address Register (MAR)?
Holds the address in memory where data is fetched or stored.
What does the Memory Data Register (MDR) temporarily hold?
Data moving between the processor and main memory.
Fill in the blank: The _______ is used to hold intermediate results of an instruction.
Accumulator
What happens during the fetch stage of the fetch-execute cycle?
The address of the next instruction is copied from the PC to the MAR.
What is the sequence of steps involved in the fetch stage?
- Copy address from PC to MAR
- Copy instruction to MDR
- Increment PC
- Copy MDR to CIR
What occurs during the decode stage of the fetch-execute cycle?
The instruction in the CIR is decoded and split into operand and opcode.
What does the opcode specify?
The operation that is to be carried out.
What does the operand hold?
- Address of the data to be used
- Actual data to be operated on
What happens during the execute stage of the fetch-execute cycle?
The instruction is executed and the result is held in the accumulator or stored in memory.
Name the three buses making up the system bus.
- Control bus
- Address bus
- Data bus
Name five special registers involved in the fetch-execute cycle.
- Program counter (PC)
- Current Instruction Register (CIR)
- Memory Address Register (MAR)
- Memory Data Register (MDR)
- Accumulator
What is the data bus?
The data bus is bi-directional as data can be sent both ways along the bus.
What determines the width of the data bus?
The width of the data bus is defined by the number of wires or lines it contains.
What happens if the data bus is the same width as a computer word?
Data can be transferred to and from memory in a single operation.
What does the width of the address bus determine?
The maximum possible memory addresses of the system.
What is the maximum number of memory addresses with an 8-bit address bus?
256 (2^8).
What is the memory capacity of an average PC in GiB?
4 GiB.
How many bytes are in 4 GiB?
2^32 bytes.
What must the address bus be for a PC with 4 GiB of memory?
32-bit address bus.
What is a word in memory?
Memory is divided up in equal units called words.
What are common word lengths?
- 8 bits
- 16 bits
- 32 bits
- 64 bits.
What is the fetch-execute cycle?
The process where the CPU fetches, decodes, and executes instructions.
What factors affect the performance of the CPU?
- Clock speed
- Number of cores
- Cache.
What is cache memory?
A small amount of superfast (but expensive) memory that stores data and instructions recently used by the processor.
What is the difference between Level 1 and Level 2 cache?
Level 1 cache is faster but smaller than Level 2 cache.
What is assembly language?
A low-level programming language closely related to machine code.
What is the basic structure of a machine code instruction?
It consists of an operation code and an operand.
What does the maximum size of the operand depend on?
The width of the address bus.
What is pipelining?
A technique used to improve performance by overlapping stages in the fetch-execute cycle.
What is parallel processing?
Using several processor cores working at the same time on different parts of the same task.
What is a dual-core computer?
A computer with two processors linked together in the same integrated circuit.
What is the theoretical advantage of a quad-core computer over a single-core computer?
It can be two or even four times faster.
What is the function of the system clock?
To synchronize the operations of the processor components.
What happens on the rising edge of the clock?
Actions are usually carried out.
How does clock speed affect performance?
The faster the clock speed, the faster a computer can fetch, decode, and execute instructions.
What is the frequency of a 4GHz processor in ticks per second?
4 billion times per second.
What is the purpose of cache memory being split into instruction cache and data cache?
So that data and instructions can be fetched simultaneously.
What is the benefit of having more cache memory?
It increases the likelihood that the next instruction or data will already be in cache.
What is a co-processor?
An extra processor used to supplement the functions of the primary processor (the CPU)
It may perform floating point arithmetic, graphics processing, digital signal processing and other functions.
What are contemporary processor architectures characterized by?
Incorporation of both von Neumann and Harvard architecture principles
Modern CPU chips often have a single main memory but divided cache memory.
What is the main memory structure in traditional desktop computers?
One main memory for holding both data and instructions
Cache memory is divided into instruction cache and data cache.
What is the primary difference between von Neumann and Harvard architectures?
Von Neumann architecture uses a single memory for both data and instructions, while Harvard architecture uses separate memories
This allows Harvard architecture to avoid bottlenecks.
Which architecture is commonly used in PCs, laptops, and servers?
Von Neumann architecture
It is based on the shared memory model.
What is a bottleneck in the context of processor architecture?
A situation where one bus for data and instructions limits performance
This occurs in von Neumann architecture.
What are the advantages of von Neumann architecture?
- Cost-effective
- Simplifies Control Unit design
- Accesses data and devices in the same way
Almost all general-purpose computers are based on von Neumann principles.
What is the purpose of Harvard architecture?
To use different sized memories and word lengths for data and instructions
It is commonly used in embedded systems and digital signal processing.
What is the key difference between CISC and RISC?
CISC uses a large instruction set, while RISC uses a minimal number of simple instructions
CISC aims to reduce lines of assembly language; RISC focuses on efficiency in clock cycles.
How is multiplication performed in CISC versus RISC?
CISC: MULT A, B; RISC: LDA R1, A; LDA R2, B; MULT R1, R2; STO R1 A
RISC requires multiple steps to accomplish the same task.
What is a GPU?
A Graphics Processing Unit is a specialized electronic circuit efficient at manipulating graphics and image processing
It consists of thousands of small cores designed for parallel processing.
What are the functions of a GPU?
- Accelerate scientific and engineering applications
- Process large blocks of visual data simultaneously
GPUs are used in various devices from mobile phones to supercomputers.
What are multi-core systems known for?
Distributing workload across multiple processor cores to achieve higher performance
They are common in personal computers and mobile devices.
What are the advantages of RISC architecture?
- Simpler hardware
- Each instruction takes one clock cycle
- Better performance at lower costs due to efficient RAM usage
Pipelining is possible due to uniform instruction timing.
What is the stored program concept?
A program must be loaded into main memory to be executed by the processor
Instructions are fetched, decoded, and executed sequentially.
What is a key characteristic of multicore processors?
They can perform several tasks in parallel
This significantly increases performance.
What is the role of the Control Unit in processor architecture?
To manage the execution of instructions and control data flow
Its design complexity varies between von Neumann and Harvard architectures.
Fill in the blank: The two main types of instruction set are ______ and ______.
[CISC], [RISC]
