Computer Data conversion SS2
SS2 Computer Studies — Computer Data Conversion
Internal Data Flow & Interactive Notes
1. Data Conversion
Data conversion is the process of changing data from one form to another so the computer can understand, store, process, or display it.
- Example: converting text to binary
- Example: converting binary to decimal
- Moving data between RAM and hard drives
2. Registers – The CPU’s Super-Fast Helpers
Registers are tiny, high-speed storage locations inside the CPU that temporarily hold data or instructions during processing.
| Register | Function |
|---|---|
| Memory Data Register (MDR) | Holds data to be stored or fetched from memory |
| Current Instruction Register (CIR) | Stores the instruction currently being executed |
| Memory Address Register (MAR) | Holds the memory address of data or instructions |
| Program Counter (PC) | Holds the address of the next instruction |
| Accumulator | Stores intermediate results from the ALU |
3. Comparison of Registers & Main Memory
| Feature | Register | Main Memory |
|---|---|---|
| Location | Inside CPU | Outside CPU |
| Speed | Extremely fast | Slower than registers but faster than secondary storage |
| Capacity | Very small (bytes) | Large (gigabytes) |
4. Buses – The Computer’s Highways
A bus is a set of connections used to transmit data, addresses, or control signals between components.
- Address Bus: Sends memory addresses from CPU (unidirectional)
- Data Bus: Transfers actual data between CPU and devices (bidirectional)
- Control Bus: Sends control signals like read/write and interrupts (bidirectional)
Example: Bus Speed Calculation
Width = 16 bits, Frequency = 133 MHz
Convert width to bytes: 16 ÷ 8 = 2 Bytes
Bus Speed = 2 × 133 × 10⁶ = 266 MB/s
5. Fetch–Execute Cycle
Fetch
Retrieve instruction from memory using PC & MAR
Decode
CU interprets the instruction in CIR
Get Data
CU fetches data from memory if needed
Execute
ALU or CU performs the operation and updates registers
6. Factors Affecting Data Transfer Speed
- RAM Size – larger RAM allows faster access
- CPU Speed & Generation – higher Hz & modern architectures process faster
- Register Size – bigger registers hold more data per operation
- Bus Width – wider bus transmits more bits at once
- Bus Frequency – higher frequency increases cycles per second
- Cache Memory – small, very fast memory for frequently used data
7. Practice Questions (Click to Reveal Answers)
1. What distinguishes registers from main memory?
Answer: A. Their location and speed
2. A bus characterized by width and frequency is defined by:
Answer: A. Transfer speed / bandwidth
3. In the fetch-execute cycle, the first step is:
Answer: C. Fetch instruction
4. Which register holds the address of the next instruction?
Answer: D. Program Counter (PC)
5. Which bus is unidirectional, carrying only memory addresses?
Answer: C. Address Bus
6. Changing data from one format to another is called:
Answer: B. Data Conversion
7. Small, very fast memory acting as a buffer between CPU and RAM is called:
Answer: C. Cache Memory
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