Short Notes:

1. ISA (Industry Standard Architecture):

• Purpose: A standard for connecting peripheral devices to computers.

• Data Bus Width: Supports 8-bit and 16-bit.
• Speed: Operates at 8 MHz.
• Uses: Commonly used for modern I/O cards such as modems and sound cards.
• Legacy: Though outdated, it remains in industrial applications due to low cost and wide
compatibility with older hardware.

2. EISA (Extended Industry Standard Architecture):

• Purpose: Developed to improve upon the ISA bus, adding more features.
• Data Bus Width: 32-bit data bus.
• Speed: Operates at 8 MHz.
• Uses: Used primarily in systems requiring enhanced I/O capabilities, like disk controllers
and graphics systems.
• Compatibility: Can accept both 8-bit and 16-bit ISA cards.

3. VESA (Video Electronics Standards Association):

• Purpose: Focused on video electronics and graphics interfaces.

• Data Bus Width: 32-bit.
• Speed: Operates at 33 MHz.
• Uses: Designed for high-performance video and graphics processing.
• Interface: Typically used for interfacing with video and disk components.

4. PCI (Peripheral Component Interconnect):

• Purpose: A modern bus standard used for connecting high-performance peripherals to

the computer's motherboard.
• Data Bus Width: 64-bit.
• Speed: Operates with plug-and-play characteristics, making it efficient for system
configuration.
• Features: Contains memory registers on the PCI board for plug-and-play functionality,
allowing the system to automatically configure devices.
• Compatibility: Replaced older bus standards like VESA, providing faster and more
flexible data transfer.

Q.What does make PCI bus so popular in the newest system?

The PCI bus is so popular in the newest system because of its plug-and-play characteristics. PCI
interface contains a series of registers, located in a small memory device on the PCI interface
that contains information about the board. This information allows the computer to automatically
configure the PCI bus. This feature is called plug-and-play.
Q.Features of Plug and Play in PCI Bus Interface:

1. Automatic Device Detection: PCI devices are automatically detected when connected to
the system, eliminating the need for manual configuration.
2. Self-Configuration: The PCI interface automatically assigns resources like memory
addresses, IRQs, and DMA channels to connected devices.
3. Ease of Use: Plug and Play allows users to add or remove devices with minimal effort,
simplifying hardware management and enhancing system flexibility.

Q. Block Diagram for PC containing PCI

Q.8(b) Write down the separate procedures for i) reading data from parallel port (LPT)
and ii) writing data to the LPT along with initialization of this port.

(i) Procedure for Reading Data from the Parallel Port (LPT)

1. Initialize the Parallel Port for Input Mode:

o The first step is to set the bidirectional bit to input mode. This is done by
sending the value 20H to the command register at address 37AH.

Code:
 MOV AL, 20H ; Load 20H into AL register (set input mode)
MOV DX, 37AH ; Load the command register address (37AH) into DX
OUT DX, AL ; Write the value of AL (20H) to the command
register at 37AH

2. Read Data from the Parallel Port:

o After the parallel port is set to input mode, you can now read data from the data
port at address 378H. Use the IN instruction to read the byte of data from the
port.

Code:

MOV DX, 378H ; Load the data port address (378H) into DX
IN AL, DX ; Read the data byte from the parallel port into AL

(ii) Procedure for Sending Data to the LPT Port (Parallel Port)

To send data to the parallel port, follow the steps below:

1. Initialize the Parallel Port for Output Mode:

o First, set the bidirectional bit to output mode by writing 00H to the command
register at 37AH.

Code:

MOV AL, 00H ; Load 00H into AL register (set output mode)
MOV DX, 37AH ; Load the command register address (37AH) into DX
OUT DX, AL ; Write the value of AL (00H) to the command
register at 37AH

2. Write Data to the Parallel Port:

o After configuring the port for output mode, you can send data through the data
port at address 378H. The OUT instruction is used to send the data byte to the
parallel port.

Code:

MOV DX, 378H ; Load the data port address (378H) into DX
MOV AL, WRITE_DATA ; Load the data to be sent into AL register
OUT DX, AL ; Write the value of AL (WRITE_DATA) to the parallel
port
LPT(In Class)

The Parallel Printer Interface (LPT), commonly used in older computer systems, is a
communication method for connecting printers and other peripherals to the computer through the
parallel port.

USB

Q.6(b) How are data encoded on the USB using NRZI coding? What is bit stuffing in the
USB? Show a bit stuffer serial data stream and the flowchart used to create it from raw
digital serial data.

How NRZI Encoding?

The USB employs NRZI (Non-Return-to-Zero, Inverted) encoding for packet transmission. In
this method, the signal level remains unchanged when transmitting a logic ‘1’, while it inverts
(toggles) the signal level whenever a logic ‘0’ is transmitted.
Bit Stuffing:

Bit Stuffing is a technique used in data transmission to maintain synchronization. If a logic '1' is
transmitted for more than 6 consecutive bits, a logic '0' is inserted after every sequence of six
consecutive '1's. This extra bit prevents the loss of synchronization over long strings of '1's. Bit
stuffing helps in ensuring the data stream stays synchronized and can be correctly interpreted by
the receiver. Data is always transmitted starting with the least significant bit.

Q.Why USB is So Popular in Modern Computer Systems?

USB (Universal Serial Bus) has gained popularity in modern computer systems due to several
key advantages:
 1. Noise Reduction: Traditional PC sound cards generated noise due to the PC’s internal
power supply. USB resolves this by allowing the sound card to have its own power
supply, eliminating the noise associated with the PC’s power system, leading to high-
fidelity sound without 60Hz hum.
2. Ease of Connection: USB allows easy connection of devices, enabling the connection of
up to 127 different devices through a single four-connection cable.
3. Versatility: The USB interface is ideal for connecting a wide range of devices,
including keyboards, sound cards, video retrieval devices, and modems.

Q.7(a) Differentiate between High-Definition Multimedia Interface (HDMI) and USB Port.

Feature HDMI USB

Transmits high-quality video
Purpose Data transfer, device connection, power
and audio

Data Transfer Varies (USB 2.0: 480 Mbps, USB 3.0: 5 Gbps,
Up to 48 Gbps (HDMI 2.1)
Speed USB 4: 40 Gbps)
Connector Types Type A (19 pins), mini, micro USB-A, USB-B, USB-C, etc.
Power Delivery Limited power (small devices) Provides power for charging devices
Entertainment and display
Primary Use General-purpose connection and charging
devices
Primarily for TVs, monitors, Used across various devices for data, peripherals,
Compatibility
projectors and charging

Q.AGP vs VGA:

• AGP: A high-speed digital interface for connecting graphics cards to system memory,
used for faster graphics performance (up to 2 GB/s).
• VGA: An analog display standard for transmitting video signals from the computer to
the monitor, mainly for visual output.

Short Note on USB (In class):

• Definition: USB is a universal serial bus used for easy user connection of various devices to
a computer or other systems.

• Connectivity: It allows access to up to 127 different devices connected simultaneously.

• Data Transmission: USB supports high-speed data transmission:

• Fast speed: 12 Mbps

• Slow speed: 1.5 Mbps
• Ideal Uses: It is commonly used for connecting devices such as modems, sound cards,
keyboards, and for video retrieval.

Short Note on AGP:(In Class)

AGP (Accelerated Graphics Port) is a high-speed interface designed for fast data transfer
between the video card and system memory, achieving speeds of up to 2 GB per second.

The key advantage of AGP over PCI bus is its ability to maintain faster data transfer speeds:

• AGP can transfer up to 2 GB per second in 8x compatible systems.

• In 4x systems, the transfer rate is over 1 GB per second.
• In comparison, the PCI bus operates at a maximum of 133 MB per second.

AGP significantly enhances graphics performance, especially for gaming and high-performance
applications, by providing higher data throughput than PCI.