COMPUTER DATA CONVERSION SS2

💻 Computer Data Conversion (SSS 2)

Source: CMPNOTE Blog

Introduction

Computers handle vast amounts of data every second. To truly understand how a computer operates, it’s important to know how data is stored, transferred, and processed internally. This topic introduces the key components and processes that make data handling and instruction execution possible in a computer system.

Definition of Terms

1. Data Conversion

Data conversion is the process of transforming computer data from one format to another. It ensures that information can be processed or transferred efficiently, such as converting text into binary or moving files between systems.

2. Registers

Registers are tiny, high-speed storage units located within the Central Processing Unit (CPU). They temporarily hold instructions, data, or addresses during processing. Registers operate under the control of the Control Unit (CU) and interact with the Arithmetic Logic Unit (ALU).

3. Address

A memory address is a unique identifier for a specific storage location. It works like a house number, telling the CPU exactly where to find or store data.

4. Bus

A bus is a set of physical connections that allows components of a computer to communicate. It acts like a data highway carrying information, signals, and control messages between devices.

Bus Characteristics

• Width: The number of bits transmitted at once.
• Speed (Frequency): The number of data transfers per second (Hertz).

Formula: Bus Speed (Bandwidth) = Width × Frequency

Example:

Find the speed of a bus that is 16 bits wide and operates at 133 MHz.

Width = 16 bits = 2 Bytes
Frequency = 133 MHz = 133 × 10⁶ Hz
Bus Speed = 2 × 133 × 10⁶ = 266 × 10⁶ Bytes/s = 266 MB/s

Types of Computer Buses

Type	Description
Internal Bus (Front-Side Bus)	Connects the CPU to RAM. Modern versions use faster direct connections.
Expansion Bus	Links external devices like USB, PCI, and SATA to the system.
Address Bus	Carries memory addresses (unidirectional).
Data Bus	Carries actual data (bidirectional).
Control Bus	Carries control signals between CPU and devices (bidirectional).

Types of Registers and Their Functions

Register	Function
Memory Data Register (MDR)	Temporarily holds data being read from or written to memory.
Current Instruction Register (CIR)	Holds the current instruction being decoded or executed.
Memory Address Register (MAR)	Stores the memory address of the data/instruction being accessed.
Program Counter (PC)	Holds the address of the next instruction to execute.
Accumulator Register	Stores intermediate results from arithmetic or logic operations.

Functions of Registers

• Hold memory addresses of data and instructions.
• Store data or instructions being processed.
• Specify I/O device addresses.
• Exchange data between CPU and I/O modules.
• Hold results of arithmetic/logic operations.
• Enable bit-shifting operations.

Differences Between Registers and Main Memory

Registers	Main Memory
Located inside the CPU	Located outside but connected to the CPU
Extremely fast	Slower than registers
Very small capacity	Large capacity (GBs)

Fetch-Execute Cycle

The Fetch-Execute Cycle describes how the CPU retrieves, decodes, and executes instructions.

1. Fetch: The PC gives the address of the next instruction to the CU, which fetches it into the CIR.
2. Decode: The CU interprets the instruction’s opcode.
3. Get Data: If needed, the CU fetches data from memory into a register.
4. Execute: The ALU or CPU component carries out the operation.

Factors Affecting Data Transfer Speed

• RAM Size: More RAM allows faster access to programs and data.
• CPU Speed & Generation: Faster CPUs can process more instructions per second.
• Register Size: Larger registers hold more data, improving performance.
• Bus Width: Wider buses allow more bits to move at once.
• Bus Frequency: Higher frequency increases data transfer rate.
• Cache Memory: Small, fast buffer between CPU and RAM that speeds up access to frequently used data.

🧠 Test Your Knowledge

Click each question to reveal the correct answer.

1️⃣ What distinguishes registers from main memory?

✅ A. Their location and speed

2️⃣ A bus characterized by width and frequency is defined by its...

✅ A. Transfer speed or bandwidth

3️⃣ In the fetch-execute cycle, what is the first step?

✅ C. Fetch the next instruction

4️⃣ Which register holds the address of the next instruction?

✅ D. Program Counter (PC)

5️⃣ Which bus is unidirectional, carrying memory addresses only?

✅ C. Address Bus

6️⃣ The transformation of computer data from one format to another is called...

✅ B. Data Conversion

7️⃣ A small, fast temporary memory that buffers CPU and main memory is called...

✅ C. Cache Memory

Conclusion

Understanding data conversion and the internal flow of data helps students grasp how computers execute instructions efficiently. Concepts like registers, buses, and the fetch-execute cycle are the foundation of all computer operations.