UG-S3 Microprocessor and PC Hardware, Second Internal Examination, October 2024

 

Section A

1. What is a microprocessor?

• A microprocessor is an integrated circuit that functions as the central processing unit (CPU) of a computer, responsible for executing instructions and performing operations such as arithmetic, logic, control, and data transfer.

 2.  What is an instruction cycle?

• The instruction cycle is the process that a CPU follows to fetch an instruction from memory, decode it, and then execute the instruction.

3.  What is an instruction?

• An instruction is a command in binary format that tells the CPU to perform a specific task, such as arithmetic, logic, or control operations.

 4. What is the instruction format of the 8085 microprocessor?

• The 8085 microprocessor instruction format includes one or more bytes that contain an opcode (operation code) and an operand (the data or address used by the instruction). The instructions can be 1-byte, 2-byte, or 3-byte long.

5.  What is the use of a branching instruction? Give an example.

• A branching instruction allows the CPU to jump to a different address and change the sequence of instruction execution. Example: JMP 2050H (jump to address 2050H).

6.  What is a motherboard?

• A motherboard is the main circuit board of a computer that houses the CPU, memory, and other components, allowing them to communicate with each other.

7.  What is a processor bus?

• A processor bus is a communication pathway that transfers data, memory addresses, and control signals between the CPU and other components.

8. How can we select a motherboard?

Selection of a motherboard should be based on compatibility with the CPU, memory type, form factor, expansion slots, chipset features, and other factors like power phases and BIOS/UEFI options.

9. What is meant by the recording media of a disk?

• The recording media of a disk refers to the material used for data storage, such as magnetic material in HDDs or flash memory in SSDs.

10.   What is the function of the logic board in an HDD?

• The logic board in an HDD controls operations, manages data transfer between the disk and the computer, and coordinates read/write actions by controlling the actuator and motor.

11.  What is NTFS?

• NTFS (New Technology File System) is a file system used by Windows that supports large files, encryption, compression, security, and disk quotas.

 12. Compare extended and expanded memory.

• Extended memory refers to memory beyond 1 MB, directly accessible by the CPU in protected mode, while expanded memory uses a paging technique to extend the accessible memory in older systems, often managed by special hardware.

                                                                                                            (10 x 2 =20 Marks)

Section B

Answer any 6 questions. Each question carries 5 marks.

13. Explain the pin diagram of Intel 8085.

Explain with a neat diagram.

The Intel 8085 microprocessor is an 8-bit microprocessor with a 40-pin dual in-line package (DIP) and operates on a +5V power supply. Here's a summary of the pin configuration:

• A15 - A8 (Pins 21-28): Higher order address bus used for the most significant byte of the address.
• AD7 - AD0 (Pins 12-19): Lower order address bus and also serves as a data bus (multiplexed).
• ALE (Pin 30): Address Latch Enable, used to de-multiplex the address-data lines.
• IO/M (Pin 31): Distinguishes between I/O and memory operations.
• RD (Pin 32): Read control signal (active low) to read data from memory or I/O devices.
• WR (Pin 29): Write control signal (active low) to write data to memory or I/O devices.
• S0, S1 (Pins 33, 34): Status signals, indicating the operation status (e.g., fetch, memory read/write).
• RESET IN (Pin 36): Resets the microprocessor when set to low.
• CLK OUT (Pin 37): Clock output to synchronize peripherals with the microprocessor.
• INTR (Pin 10), RST 7.5, 6.5, 5.5 (Pins 7, 6, 5): Interrupt pins for external devices to interrupt the microprocessor.

A neat diagram shows how these pins are arranged and connected, illustrating their functions clearly.

 

14. What is meant by an interrupt? Explain with examples.

An interrupt is a signal that temporarily halts the current CPU operations, allowing the CPU to address a different task (often higher priority). Once the interrupt is serviced, the CPU resumes its previous operations.

Examples:

• Hardware Interrupt: Triggered by hardware components like a keyboard or mouse (e.g., pressing a key sends an interrupt to the CPU).
• Software Interrupt: Triggered by executing specific instructions in a program, like system calls.

In the 8085, interrupts like RST 7.5, RST 6.5, and INTR can be used to handle external devices.

 

15. Explain addressing modes.

Addressing modes define how the operand of an instruction is specified. Common addressing modes include:

• Immediate Addressing Mode: The operand is given directly in the instruction (e.g., MVI A, 05H).
• Register Addressing Mode: The operand is in one of the registers (e.g., MOV A, B).
• Direct Addressing Mode: The memory address of the operand is given explicitly (e.g., LDA 2050H).
• Indirect Addressing Mode: The address of the operand is held in a register pair (e.g., MOV A, M where M is the memory location pointed by HL pair).
• Implied Addressing Mode: The operand is implicit in the instruction (e.g., CMA complements the accumulator).

 

16. Explain about Coprocessor.

A coprocessor is a specialized processor that works alongside the main CPU to perform specific tasks, such as floating-point arithmetic, graphics processing, or encryption. It offloads complex tasks from the CPU to increase system performance.

Example: The Intel 8087 was a coprocessor for the Intel 8086/8088, used for floating-point calculations, significantly improving computation speed in mathematical operations.

 

17. Briefly explain about chipset and super I/O chip.

• Chipset: A chipset is a group of integrated circuits that manage data flow between the processor, memory, and peripherals. It consists of:
• Northbridge: Manages communication between the CPU, RAM, and high-speed graphics ports.
• Southbridge: Handles I/O functions like USB, audio, SATA, and other peripherals.
• Super I/O Chip: This is a chip that manages slower I/O devices such as keyboards, mice, serial ports, parallel ports, and sometimes sensors like temperature or fan control. It is typically found on the motherboard in older systems.

 

18. Differentiate between system buses and memory buses.

• System Bus: This refers to the data, address, and control buses that facilitate communication between the CPU and all other components (including memory and I/O devices). It is the main pathway for data transfer in the system.
• Memory Bus: A subset of the system bus specifically dedicated to transferring data between the CPU and RAM. It consists of address lines for memory addresses and data lines for data to be read or written.

 

19. Write about disk geometry.

Disk geometry refers to the physical and logical structure of a hard disk drive. It includes:

• Cylinders: Concentric circles on the surface of each disk platter.
• Heads: The read/write mechanism that accesses data.
• Sectors: The smallest storage unit on a disk, typically 512 bytes.

The geometry is defined by the number of cylinders, heads, and sectors per track, which determine how data is organized on the disk.

 

20. Give a description about VFAT and long filenames in VFAT.

VFAT (Virtual File Allocation Table) is an extension of the FAT file system that supports long filenames (up to 255 characters) in addition to the older 8.3 format used by FAT. VFAT allows for the use of mixed case, spaces, and non-ASCII characters in filenames without breaking backward compatibility with FAT16 and FAT32.

 

21. Compare SIMM, DIMM, and RIMM.

• SIMM (Single In-line Memory Module): Has a single row of memory chips and provides a 32-bit data path. It was used in older systems.
• DIMM (Dual In-line Memory Module): Has separate electrical contacts on each side of the module, providing a 64-bit data path. DIMMs are commonly used in modern computers.
• RIMM (Rambus In-line Memory Module): A high-speed memory technology developed by Rambus, used in some systems in the early 2000s. It was known for being faster than DIMM but also more expensive and eventually fell out of favor due to high costs

6 x 5 = 30 Marks)

 

Section C

Answer any 2 questions. Each question carries 15 marks

22. Explain the instruction set of 8085.

The instruction set of the Intel 8085 microprocessor consists of 246 instructions, grouped into five categories based on the type of operations:

1. Data Transfer Instructions: Move data between registers, memory, or input/output devices.
• Example: MOV A, B (Copy contents of register B into register A).
2. Arithmetic Instructions: Perform arithmetic operations like addition, subtraction, increment, and decrement.
• Example: ADD B (Add contents of register B to the accumulator A).
3. Logical Instructions: Perform logical operations like AND, OR, XOR, and compare.
• Example: CPI 05H (Compare immediate value 05H with accumulator A).
4. Branching Instructions: Alter the flow of execution by jumping to specific memory locations.
• Example: JMP 2050H (Jump to address 2050H).
5. Control Instructions: Control operations like interrupts, halt, and enabling/disabling the CPU's state.
• Example: DI (Disable interrupts).Explain each group

The instruction set includes both 1-byte, 2-byte, and 3-byte instructions, depending on the opcode and the operands involved.

 

23. Explain the expansion slots.

Expansion slots are connectors on the motherboard that allow additional hardware (expansion cards) to be attached, providing new functionality or enhancing existing capabilities.

Common types of expansion slots include:

. Explain each in detail.

·       PCI (Peripheral Component Interconnect) Slot

·       PCI Express

·       AGP (Accelerated Graphics Port) Slot

·       ISA (Industry Standard Architecture) Slot

·       VESA (Video Electronics Standards Association) Local Bus

·       MCA

 

 

Expansion slots allow users to upgrade their systems by adding peripherals like graphics cards, network interfaces, sound cards, or additional storage.

 

24. Explain the different components of an HDD (Hard Disk Drive).

A hard disk drive (HDD) consists of several key components:

1. Platters: Circular disks coated with magnetic material where data is stored.
2. Spindle: A motor that spins the platters at high speeds (e.g., 5400 RPM, 7200 RPM).
3. Read/Write Heads: Magnetic heads that read data from or write data to the platters. Each platter typically has two heads, one for each side.
4. Actuator Arm: Moves the read/write heads across the platters to access different tracks of data.
5. Actuator: The mechanism that moves the actuator arm, usually controlled by a voice coil motor.
6. Logic Board: The printed circuit board (PCB) that controls the overall functioning of the drive, including communication with the computer.
7. Cylinders, Tracks, and Sectors: These are logical divisions on the platters where data is stored. Cylinders are the vertical stacks of tracks across all platters.

Together, these components allow for the mechanical reading and writing of data on the HDD.

 

25. Discuss about each one: (a) Conventional memory, (b) UMA, (c) HMA.

(a) Conventional Memory:
Conventional memory refers to the first 640 KB of memory in a PC, used for running DOS and basic system functions. It was the only memory accessible in real mode on early x86 systems. This memory is critical for the operation of legacy systems and older software.

(b) UMA (Upper Memory Area):
The UMA refers to the memory range between 640 KB and 1 MB. This area was reserved for BIOS, system firmware, and I/O device mapping. DOS systems could use special techniques (like memory managers) to utilize some of this space for loading drivers or TSR (Terminate and Stay Resident) programs.

(c) HMA (High Memory Area):
HMA is a special region that refers to the first 64 KB of extended memory just beyond the 1 MB boundary (starting at 1024 KB). On systems with an Intel 80286 or newer CPU, HMA could be accessed in real mode using special techniques, and DOS could load parts of itself into HMA to free up conventional memory for other programs. This was facilitated by the use of memory managers like HIMEM.SYS in DOS.

            (2 X 15 = 30 Marks)