Question

The following table represents the addresses and contents (using hexadecimal notation) of some cells in a machine's main memory. Starting with this memory arrangement, follow the sequence of instructions and record the final contents of each of these memory cells: Step 1. Move the contents of the cell whose address is \(0 x 03\) to the cell at address \(0 \times 00\). Step 2. Move the value \(0 \times 01\) into the cell at address \(0 \mathrm{x} 02\). Step 3. Move the value stored at address \(0 \mathrm{x} 01\) into the cell at address \(0 \mathrm{x} 03\).

Short answer

Content at 0x00 becomes 0x(content from 0x03); 0x02 becomes 0x01; 0x03 becomes 0x(content from 0x01).

Step-by-step solution

Understanding the Initial Memory Setup

Before starting with the steps, it's important to understand the initial setup of the memory. Identify the memory addresses and their corresponding initial content values, typically given in a table format. Make sure you know the addresses 0x00, 0x01, 0x02, and 0x03 are accessible for this operation.

Execute Move Operation from 0x03 to 0x00

Read the content of the memory cell at address 0x03. Move this content to the memory cell at address 0x00 by replacing the previous content. Record the content that is now at 0x00, without altering the content at 0x03.

Insert a New Value at 0x02

Write the new value of 0x01 directly into the cell at address 0x02. This operation overwrites the existing content of the memory cell at 0x02. Record the new content value, which is now 0x01.

Shift Value from 0x01 to 0x03

Check the current content of the cell at address 0x01. Move this value into the memory cell at 0x03. Note that this will overwrite the content present at 0x03 without affecting other cells.

Key concepts

Hexadecimal Notation

Hexadecimal notation is a base-16 number system. Unlike the decimal system that uses digits 0 to 9, hexadecimal adds the letters A to F (representing values 10 to 15).
Hexadecimal is often used in computing because it can represent every byte (8 bits) as two consecutive hexadecimal digits. This makes it more compact and readable. In our context, memory addresses and contents are shown in hexadecimal, such as 0x03 or 0x01. The prefix "0x" is used to indicate that the number that follows is in hexadecimal. It allows programmers to quickly identify the base of the number.
Transitioning between binary, octal, decimal, and hexadecimal helps in understanding how computer systems process data and execute instructions.

Memory Cell Addressing

Memory in a computer is organized in a sequence of cells, each identified by a unique address. Each memory "cell" can store a specific amount of data, commonly a byte, which is 8 bits.
The address, often presented in hexadecimal, acts like a "home address" for the data stored there. In our exercise, addresses like 0x00, 0x01, 0x02, and 0x03 are used to locate specific memory cells. Proper memory addressing allows software to read from and write to memory locations accurately. It ensures that data is retrieved or stored precisely where intended. Mistakes in address management can lead to errors and unpredictable program behavior, which highlights the importance of accurate and efficient memory cell addressing.

Memory Content Manipulation

Memory content manipulation involves changing the data stored at a specific memory location. This is done through operations like move, copy, or set, such as those outlined in programming instructions. Consider the following steps to understand basic memory manipulation:

• Move content between cells: Here, the contents of one cell are transferred to another, replacing the existing data. This operation doesn't affect the original content unless explicitly stated.
• Insert new values: A new value can overwrite the existing data at a specific memory address.
• Overwrite operations: Such actions replace older data with new data that may be read or written from elsewhere.

Mastering memory manipulation allows for better memory management, reducing inefficiencies and improving processing speed.

Instruction Execution in Memory

Instruction execution in memory refers to the process by which a computer performs operations based on instructions provided through a set program.
An instruction could be to move data, store data, or perform calculations. Here, the operation steps are executed in sequence, such as moving data from one cell to another. To ensure a seamless execution:

• Sequence is key: Instructions must be followed in the correct order to achieve the desired results.
• Memory accuracy: Ensure memory addresses are precisely targeted to avoid unintended data alteration or loss.
• Data integrity: Always verify that the instructions are appropriately altering the memory contents as intended after execution.

Understanding how instructions are executed in memory is fundamental to programming and optimizing computer operations.