Computer Architecture: Registers and Addressing

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Questions and Answers

What is indicated by an instruction containing an immediate operand?

The operand is located in a direct address.

The operand is found in a memory address.

The operand is the value itself specified in the instruction. (correct)

The operand address is indirectly specified.

In which addressing mode does the instruction code specify the address of a memory word that contains the operand's address?

Indirect addressing (correct)

Immediate addressing

Direct addressing

What is a complete instruction set defined by?

Including a range of arithmetic, logic, and control instructions (correct)

Focusing solely on processor register manipulations

Having at least one instruction for every operation

Containing only input and output instructions

What determines if an instruction is a register-reference type or an input-output type?

The bit in position 15 Signup and view all the answers

What does the mode field in an instruction specify?

The method for determining the operand of the effective address Signup and view all the answers

What does the value of the bit 'I' signify in a memory reference instruction?

It differentiates between direct and indirect addressing. Signup and view all the answers

What is a primary purpose of processor registers in a CPU?

To quickly accept, store, and transfer data and instructions currently in use Signup and view all the answers

Which of the following instructions is recognized by the opcode '111' with a 0 in the leftmost bit?

Register Reference Instruction Signup and view all the answers

What must the three operation code bits in positions 12 through 14 be for the instruction to be classified as a specific type?

111 Signup and view all the answers

Which instruction category is primarily responsible for changing the execution sequence of a program?

Program control instructions Signup and view all the answers

How do processor registers contribute to instruction execution?

They calculate the address of the next instruction after execution Signup and view all the answers

What is the primary purpose of the operation code (opcode) field in an instruction?

To specify the operation that needs to be performed. Signup and view all the answers

What do memory locations consist of in a computer's memory?

Cellular storage units known as flip-flops Signup and view all the answers

When using direct addressing, what does the instruction code's address field specify?

The location of the operand directly. Signup and view all the answers

Which statement is true regarding the number of address fields in an instruction?

It varies based on the internal organization of the registers Signup and view all the answers

What occurs if the three operation code bits in positions 12 through 14 do not equal 111?

The instruction is a memory-reference type Signup and view all the answers

Which of the following best defines the role of registers in the context of computer memory?

Registers temporarily hold data and instructions for immediate processing Signup and view all the answers

What is the size of the operation code part in the instruction format discussed?

3 bits Signup and view all the answers

Which instruction type uses 12 bits to specify the address and 1 bit for the addressing mode?

Memory Reference Instruction Signup and view all the answers

What type of data can be held by a processor register?

A memory address and any data type, including instructions Signup and view all the answers

What must be true for data to be effectively processed by the computer?

Data must be moved between memory and processor registers Signup and view all the answers

In what manner do input and output instructions function in a computer system?

They facilitate communication between the computer and user Signup and view all the answers

Study Notes

Operand Addressing Modes

Operand of effective address is determined through a mode field.
Instruction lengths vary and can contain different numbers of addresses based on CPU configuration.
Operand addressing can be immediate, direct, or indirect.

Computer Registers

Registers are a form of high-speed memory for immediate data and instruction handling by the CPU.
Processor registers can store instructions, addresses, or any data types, including characters.
Registers enable data manipulation and compute addresses for upcoming instructions.

Load Instruction (LD)

Registers receive data from a common bus based on which register's LD input is activated during the clock pulse transition.

Computer Instructions

Basic computers utilize three instruction code formats with a total of 16 bits: 3 bits for opcode and 13 bits for operation specification.

Instruction Code Formats

Memory Reference Instruction:
- 12 bits specify memory address.
- 1 bit indicates addressing mode (0 for direct, 1 for indirect).
Register Reference Instruction:
- Identified by opcode 111 and begins with 0.
- Remaining bits denote operation to execute.
Input-Output Instruction:
- Recognized by opcode 111 beginning with 1.
- Other bits specify the specific I/O operation.

Instruction Format Components

Includes an operation code field for the operation to perform.
Contains an address field for designating memory addresses or registers.
Opcode bits in positions 12-14 should equal 111; bit 15 indicates the type of instruction (register or input-output).

Instruction Set Completeness

A complete instruction set covers:
- Arithmetic, logical, and shift instructions.
- Instructions for transferring data between memory and registers.
- Program control and status-checking instructions.
- Input/Output instructions facilitating user interaction.

Memory Structure

Memory comprises millions of storage cells (flip-flops) capable of holding a single bit (0 or 1).
A collection of bits forms a word of information, defined by a specific word length (n).

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Description

This quiz explores the concepts of computer registers and the various modes of effective address determination. Learn how instructions of different lengths and address fields impact the CPU's performance and organization. Test your knowledge of key terms and their applications in computer architecture.