CPU Memory and Registers Quiz

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Questions and Answers

What is the primary purpose of the Program Counter (PC) in the CPU?

To store data temporarily

To execute the current instruction

To hold the address of the next instruction (correct)

To manage input and output operations

Which component is NOT part of the instruction format?

Op Code

Addressing Mode

Address of Operand

Data Register (correct)

What happens during the decoding process if the addressing mode value is non-zero?

The instruction is ignored

The operand is fetched from a register (correct)

The instruction is executed immediately

The operand is fetched directly from memory

Which statement about the conversion from decimal to binary is accurate?

The process ends when the quotient reads zero Signup and view all the answers

What is the role of General Purpose Registers in the CPU?

To hold intermediate data and results Signup and view all the answers

Which of these number systems represents the base 8?

Octal Signup and view all the answers

During the initial step sequence, what is the first action performed with the Program Counter?

Transfer its value to the Address Register (AR) Signup and view all the answers

What type of reference occurs if the addressing mode is evaluated as zero during instruction decoding?

A direct memory reference Signup and view all the answers

What is the first step in converting a decimal number to hexadecimal?

Divide by 16 Signup and view all the answers

Which method is used to convert a binary number to decimal?

Multiply each digit by its power of 2 Signup and view all the answers

What is the final step of Booth's Multiplication Algorithm?

Terminate when the sequence counter reaches 0 Signup and view all the answers

In the instruction cycle, which stage follows the instruction decode stage?

Operand Fetch Signup and view all the answers

What does the immediate addressing mode utilize?

Direct value as the operand Signup and view all the answers

What is the correct sequence of steps for Booth's Multiplication Algorithm?

Shift A, Q right by 1 bit, then update SC Signup and view all the answers

Which of the following is NOT a step in the instruction cycle?

Operand Decode Signup and view all the answers

What operation is performed during the 'Write Back' stage of the instruction cycle?

Store the result in memory Signup and view all the answers

What is referred to as a three address instruction?

An instruction that performs three memory referencing. Signup and view all the answers

Which component of the CPU is responsible for storing the results of operations performed by the ALU?

Accumulator Signup and view all the answers

How does a ripple carry adder function?

By cascading full adders in a chain where carry bits ripple. Signup and view all the answers

What role does the control unit play within the CPU architecture?

It controls the entire CPU and manages the instruction cycle. Signup and view all the answers

Which of the following best describes a CPU bound instruction?

An instruction that is executed primarily by the CPU. Signup and view all the answers

What is the function of the Memory Address Register (MAR)?

To store the address of the memory location being accessed. Signup and view all the answers

In a 32-bit ALU, how are the individual 1-bit ALUs connected?

In a parallel configuration with a multiplexer controlling outputs. Signup and view all the answers

What defines the CPU architecture?

The arrangement and interconnection of CPU components. Signup and view all the answers

What is the primary role of the control unit in the CPU?

To generate control signals for operations Signup and view all the answers

Which of the following best describes microprogramming?

A technique to design control units via simpler micro-instructions Signup and view all the answers

In the memory hierarchy, which type of memory is the fastest?

Registers Signup and view all the answers

What distinguishes Dynamic RAM (DRAM) from Static RAM (SRAM)?

DRAM needs a refresh circuit, while SRAM does not Signup and view all the answers

For a 512 x 8 KB ROM chip, how many address lines are necessary for access?

12 address lines Signup and view all the answers

Which statement about Read-Only Memory (ROM) is accurate?

Data in ROM can only be read, not written Signup and view all the answers

What is the size required for address lines when accessing a RAM chip of size 128 x 8 KB?

7 address lines Signup and view all the answers

How does the memory hierarchy generally rank memory types from fastest to slowest?

Registers, Cache, Main Memory, ROM, Secondary Storage Signup and view all the answers

How many address lines are needed for the RAM specified?

7 Signup and view all the answers

What is the primary benefit of using instruction pipelining?

Increases the overall instruction execution speed Signup and view all the answers

Which architecture allows for multiple programs to run concurrently?

Multiprogramming Signup and view all the answers

What is one advantage of a micro-programmed control unit over a hardwired control unit?

It is easier to modify and update Signup and view all the answers

In a parallel processing architecture, what is the effect of multiple cores in a CPU?

Enhanced processing power and performance Signup and view all the answers

Which component is responsible for executing micro-instructions in a micro-programmed control unit?

Control memory Signup and view all the answers

What is a significant characteristic of the hardwired control unit?

It is constructed with logic circuits for faster operation Signup and view all the answers

What happens during the first stage of instruction pipelining?

Fetch the next instruction Signup and view all the answers

Study Notes

CPU Memory

There are two types of memory: instruction memory and data memory.
The CPU fetches instructions from instruction memory and data from data memory.

Registers

Registers are located within the CPU, providing fast access to data.
Two types: General Purpose Registers and Special Purpose Registers.
Program Counter (PC) holds the address of the next instruction to be executed.
Stack Pointer (SP) manages the stack.

Instruction Format

Instructions are broken down into opcode, address of operand, and addressing mode.
Opcode specifies the type of instruction.
Address of Operand points to the data the instruction will operate on.
Addressing Mode determines how the address of the operand is calculated.

Initial Step Sequence

The Program Counter (PC) is initialized to 0, pointing to the first instruction.
The address from the PC is transferred to the Address Register (AR).
The instruction at the address is fetched and placed in the Instruction Register (IR).
The PC is incremented to point to the next instruction.

Instruction Decoding

After fetching, the instruction is decoded to determine the type of operation and the addressing mode.
If the addressing mode indicates a memory reference, the operand is fetched from memory.
If the addressing mode indicates a register reference, the operand is fetched from the corresponding register.

Instruction Execution

Once the instruction is decoded and operands are fetched, the instruction is executed by the ALU.
The result of the execution is written back to either memory or a register.

Number Systems

Binary: Base 2 (0, 1)
Octal: Base 8 (0-7)
Decimal: Base 10 (0-9)
Hexadecimal: Base 16 (0-9, A-F)

Decimal Conversion

Converting decimal numbers to other bases involves repeated division by the base and recording the remainders in reverse order.
- Decimal to Binary: Divide by 2.
- Decimal to Octal: Divide by 8.
- Decimal to Hexadecimal: Divide by 16.

Other Base Conversions

Binary to Decimal: Multiply each binary digit by its corresponding power of 2 and sum the results.
Octal to Decimal: Multiply each octal digit by its corresponding power of 8 and sum the results.
Hexadecimal to Decimal: Multiply each hexadecimal digit by its corresponding power of 16 and sum the results.

Converting to Non-Decimal

To convert from octal to binary, convert each octal digit to its binary equivalent.
To convert from hexadecimal to octal, convert each hexadecimal digit to its equivalent binary number.

Booth's Multiplication Algorithm

This algorithm multiplies signed integers efficiently.
It involves repeated addition/subtraction of the multiplicand based on the current bits of the multiplier.
The algorithm utilizes a sequence counter (SC) to track the number of iterations.

Instruction Cycle

The execution of an instruction involves five stages:
- Fetch: Retrieve the instruction from memory.
- Decode: Interpret the instruction.
- Fetch Operand: Retrieve the data needed for the operation.
- Execute: Perform the operation on the data.
- Write Back: Store the result of the operation.

Addressing Modes

Immediate Addressing: The operand is directly encoded in the instruction.
Register Direct Addressing: The operand is stored in a specific register.
Register Indirect Addressing: The register holds the memory address of the operand.
Memory Direct Addressing: The operand is stored in a specific memory location.
Memory Indirect Addressing: The memory address of the operand is stored in another memory location.
Relative Addressing: The operand's address is relative to the current program counter.

Instruction Classification

Instruction classification based on memory accesses:
- Three Address Instruction: Three memory references per instruction.
- Two Address Instruction: Two memory references per instruction.
- One Address Instruction: One memory reference per instruction.

CPU Bound Instruction

CPU-bound instructions require significant processing time on the CPU.
They are not limited by I/O operations.

Arithmetic and Logic Unit (ALU)

The ALU performs arithmetic and logical operations.
A 32-bit ALU consists of 32 1-bit ALUs operating in parallel.

Ripple Carry Adder

A ripple carry adder adds multiple-bit numbers by cascading full adders.
The carry output of each full adder is passed as input to the next full adder.

CPU Architecture

The CPU architecture details the structure and interconnections of CPU components.
- ALU performs arithmetic and logic operations.
- Accumulator stores the ALU result.
- Instruction Register (IR) temporarily holds the instruction.
- Program Counter (PC) tracks the next instruction.
- Memory Data Register (MDR) buffers data between CPU and memory.
- Memory Address Register (MAR) stores the memory address being accessed.
- Control Unit directs the overall CPU operation.
- Serial I/O Controller manages input/output operations.
- Stack Pointer manages the stack.
- Interrupt Controller handles interrupts.
- Timer manages timing information.

Control Unit

The control unit interprets instructions from the IR to generate control signals for the CPU.
It directs the operation of ALU, registers, memory, and other units.

Micro-Programmed Control Unit

Microprogramming breaks down instructions into simpler micro-instructions.
These micro-instructions are stored in a control memory.
The control unit reads and executes the micro-instructions to control the CPU.
Provides flexibility for modification by changing the micro-program.

Memory Organization

Memory hierarchy:
- Registers (fastest, smallest).
- Cache (fast, small).
- Main Memory (large, slow).
- Secondary Storage (permanent, largest, slowest).
Memory classification:
- Read-Only Memory (ROM): Data can only be read.
- Read/Write Memory (RAM): Data can be both written and read.

Types of RAM

Dynamic RAM (DRAM): Uses capacitors to store data requiring refresh circuits.
Static RAM (SRAM): Uses latches for data storage, faster but less dense than DRAM.

Connecting RAM and ROM

The CPU can access both RAM and ROM.
The number of address lines needed for each memory depends on its size.

Memory Organization Diagram

Demonstrates the interconnection between CPU, RAM, ROM, and decoders.
The number of address lines for each memory chip depends on its capacity.
Decoders are used to select the correct memory chip.

Parallel Processing Architecture

Allows processing multiple instructions simultaneously.
Multiprogramming: Multiple programs loaded into memory, the CPU switches between them to utilize available processing time.

Multi-Core Architecture

CPUs can have multiple cores, enabling parallel processing of instructions.
Each core can independently execute instructions, increasing overall processing power.

Instruction Pipeline

Instruction execution stages are overlapped to improve performance.
The instruction cycle is divided into stages, each responsible for a specific task.
Stages can operate concurrently, leading to faster execution.

Micro-Programmed Control Unit Explained

Micro-instructions define the sequence of steps for each instruction.
Micro-instructions are stored in control memory, allowing flexibility for modification.

Micro-Programmed Vs. Hardwired Control Unit

Micro-programmed control unit offers flexibility due to software modification.
Hardwired control unit, built with logic circuits, is faster but less flexible.

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Description

Test your knowledge of CPU memory types, the role of registers, and the instruction format. This quiz covers how the Program Counter and Stack Pointer function within the CPU. Perfect for students learning computer architecture.