Little Man Computer Overview

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Questions and Answers

What is the purpose of the instruction location counter in the Little Man Computer?

To sequentially execute instructions from mailboxes (correct)

To manage data input from the user

To store the results of calculations

To reset the calculator after operations

Which instruction must the Little Man execute first to begin adding two numbers together?

OUTPUT

INPUT (correct)

LOAD

STORE

Why can't the Little Man read a second number into the calculator after the first number has been loaded?

The calculator only supports one number at a time

The instruction does not permit multiple inputs

This would overwrite the first number in the calculator (correct)

The out basket cannot handle more than one number

What happens to the instruction location counter after the Little Man completes an instruction?

It increments by one Signup and view all the answers

Which instruction is responsible for storing the first number read from the in basket?

STORE Signup and view all the answers

What is the intended outcome after the Little Man executes a program that adds two numbers?

The sum is placed in the out basket Signup and view all the answers

How does the user restart the program in the Little Man Computer?

By resetting the instruction location counter to 00 Signup and view all the answers

Which category of instructions does the COFFEE BREAK belong to in the Little Man Computer?

Control instructions Signup and view all the answers

Why must the first number be saved at Mailbox 99 instead of a location within the program?

Storing it within the program would overwrite an instruction there. Signup and view all the answers

What does it mean that the Little Man cannot distinguish between instructions and data?

Both instructions and data are represented as three-digit numbers. Signup and view all the answers

What is the first instruction the Little Man executes?

READ Signup and view all the answers

What happens if data is stored in a program area the Little Man will execute?

The Little Man will attempt to execute the data as an instruction. Signup and view all the answers

What is the primary function of the program's output step?

To send the result to the out basket for retrieval. Signup and view all the answers

What limitation does the current instruction set impose on programming?

It lacks the ability to use branching or looping mechanisms. Signup and view all the answers

How does the program ensure that it can be rerun effectively?

By placing data outside the program’s execution area. Signup and view all the answers

Given the sequential nature of the program, what is the consequence of modifying an instruction?

It allows programmers to create more complex operations. Signup and view all the answers

What is the purpose of the BRP instruction in the given LMC program?

To branch to a specific instruction if the result is positive Signup and view all the answers

Which instruction in the LMC program directly results in outputting the result?

OUT 902 Signup and view all the answers

What happens if the COB instruction is omitted from the LMC program?

The Little Man will attempt to execute data as instructions Signup and view all the answers

What is the purpose of the INPUT instruction in the LMC model?

To retrieve a number from the in basket and update the calculator Signup and view all the answers

In the instruction cycle, what does the fetch portion involve?

Reading the current instruction from the mailbox Signup and view all the answers

What type of instruction is the SUB instruction in the context of the LMC program?

Arithmetic instruction Signup and view all the answers

What happens to the original number in the calculator after an OUTPUT instruction?

It is unchanged Signup and view all the answers

What is the main purpose of storing the results in mailbox locations 10 and 11 in the LMC program?

To serve as temporary storage for inputs Signup and view all the answers

Which opcode corresponds to the COFFEE BREAK instruction in the LMC model?

0 Signup and view all the answers

Which operation would be performed if the result of a subtraction is negative?

The original order of subtraction will be reversed Signup and view all the answers

In what way do INPUT and OUTPUT instructions differ according to the LMC model?

INPUT instructions update the calculator, while OUTPUT instructions do not Signup and view all the answers

How does the LMC model indicate that a number is negative during a calculation?

By providing a minus sign as a flag Signup and view all the answers

Identify the instruction responsible for halting the execution of the LMC program.

COB 000 Signup and view all the answers

What is the function of the op code used for the OUTPUT instruction in the LMC?

To transfer data to an output device Signup and view all the answers

Which aspect of the INPUT instruction is highlighted by its ability to only handle one slip of paper at a time?

The sequential nature of handling inputs Signup and view all the answers

What limitation does the LMC model have regarding the handling of negative numbers?

Negative signs cannot be stored due to a three-digit system Signup and view all the answers

What is the primary function of the calculator in the Little Man Computer?

To enter and temporarily hold numbers as well as perform addition and subtraction Signup and view all the answers

How does the Little Man Computer receive input from the user?

By reading slips of paper with three-digit numbers placed in the in basket Signup and view all the answers

What limitation does the Little Man Computer's calculator have regarding the display of numbers?

It cannot display any fractions or decimals Signup and view all the answers

What must occur first in the instruction cycle?

The fetch operation Signup and view all the answers

Which of the following describes the correct sequence of steps for the LOAD instruction execution?

Fetch instruction, look at mailbox, punch number into the calculator, increment location counter Signup and view all the answers

Which of the following statements about communication in the Little Man Computer environment is true?

All interactions must be conveyed using three-digit numbers. Signup and view all the answers

What differentiates the ADD and SUBTRACT instructions from the LOAD instruction?

They change the operation performed in the execute step Signup and view all the answers

What role does the Little Man play in the Little Man Computer setup?

To perform tasks defined by the three-digit instruction codes Signup and view all the answers

Which of the following features does NOT apply to the Little Man Computer’s calculator?

It can handle numbers larger than three digits. Signup and view all the answers

When can the Little Man increment the instruction location counter?

Anytime after the fetch operation has occurred Signup and view all the answers

What happens during the fetch phase of the instruction cycle?

The Little Man looks at the instruction location counter Signup and view all the answers

How is the reset function implemented in the Little Man Computer?

Using the reset button located outside the mailroom for the instruction location counter Signup and view all the answers

What is true about the steps within an instruction?

Certain steps must follow others strictly Signup and view all the answers

In the fetch phase, which mailbox location does the Little Man refer to before fetching the instruction?

The mailbox with the address indicated by the location counter Signup and view all the answers

Which of the following statements is correct regarding the arithmetic instructions?

They involve entering the result of an operation into the calculator Signup and view all the answers

Study Notes

The Little Man Computer

The Little Man Computer (LMC) is a simple model of a computer
It uses a calculator, mailboxes, and a counter
The calculator performs calculations
Mailboxes store data
The counter holds the address of the next instruction
Instructions use a single digit (op code) to indicate the operation
Other two digits specify the mailbox address
The Little Man performs the instructions

Instructions

LOAD (op code 5): Reads the three-digit number from the specified mailbox into the calculator.
STORE (op code 3): Copies the three-digit number from the calculator to the specified mailbox.
ADD (op code 1): Adds the three-digit number in the specified mailbox to the number in the calculator.
SUBTRACT (op code 2): Subtracts the three-digit number in the specified mailbox from the number in the calculator.
INPUT (op code 9, address 01): Reads a three-digit number from the input basket and places it in the calculator.
OUTPUT (op code 9, address 02): Writes the three-digit number in the calculator to the output basket.
COFFEE BREAK (op code 0): The Little Man takes a rest.

Extended Instructions

Branch Unconditionally (JUMP): Changes the instruction location counter to a new address.
Branch on Zero: Changes the instruction location counter if the value in the calculator is zero.
Branch on Positive: Changes the instruction location counter if the value in the calculator is positive.

Von Neumann Architecture

A computer architecture where memory stores both programs and data.
Memory is addressed linearly.
Instructions are executed in sequence unless a branch instruction changes the sequence.
The LMC is an example of a von Neumann architecture.

Instruction Cycle

Fetch: The processor fetches the instruction from memory.
Execute: The processor performs the instruction.

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Description

Explore the fundamentals of the Little Man Computer (LMC) model in this quiz. Learn about its basic operations, including load, store, add, and subtract, along with the role of the calculator, mailboxes, and counter. Test your understanding of how this simple computer model functions.