MICROPROCESSORS

Question 1

What is a microcomputer

Answer 1

a less powerful mini computer that contains a microprocessor as its central processor.

Question 2

What are the advantages of microcomputers

Answer 2

can functionally replace thousands of random logic chips,
but occupies a much lesser space,
costs much lesser
and the number of device interconnections being fewer in it, is much more reliable.

Question 3

What is a microprocessor?

Answer 3

an integrated circuit designed to function as the CPU of a microcomputer

Question 4

Define the architecture of a microprocessor and draw a diagram depicting the same

Answer 4

organizational structure of μP(microprocessor), which determines how it operates, is known as its architecture.

See notes for pic

Question 5

What is a word in the context of a microprocessor?

Answer 5

μC operates on a group of bits which are referred to as a word.
• The number of bits making-μP a word varies with the μP.
• Common word sizes are 4, 8, 12 and 16 bits (μPs with 32 bit-word have also of late entered the market).

Question 6

What are bytes and nibbles

Answer 6

byte-8 bits

nibble- 4 bits

Question 7

What are buses?

Answer 7

data highways that allow exchange of words between
the interconnecting blocks of the μP.
• A bus has a wire or line for each bit and thus allows exchange of all bits of a word in parallel.

*The width of a bus is the number of signal lines that constitute the bus.

Question 8

What are the different types of buses?

Answer 8

Address bus - carries memory addresses from the processor to other components such as primary storage and input/output devices.
Data bus - carries the data between the processor and other components.
Control bus - carries control signals from the processor to other components.

Question 9

What are internal registers used for in microprocessors?

Answer 9

temporary storage of data, instructions and addresses during execution of a program.

Question 10

List the types of registers found in the Intel 8085 microprocessor

Answer 10

• Accumulator (Acc) or Result Register - This is an 8-bit register used in various arithmetic and logical operations.
• General Purpose Registers or Scratch Pad Memory - There are six general purpose 8-bit registers that can be used by the programmer for a variety of purposes.
• Instruction Register (IR) - This 8-bit register stores the next instruction to be executed.
• Program Counter (PC) - This is a 16-bit register which holds the address of the next instruction that has to be fetched from the main memory and loaded into the instruction register.
• Stack Pointer (SP) - This is also a 16-bit register and is used by the programmer to maintain a stack in the memory while using subroutines.
• Status Register or Condition Flags - A status register consisting of a few flip-flops, called as condition flags.
• Dedicated Registers - Several other registers are incorporated in the μP for its internal operation. They cannot be accessed by the programmer and hence do not concern much a μP user.

Question 11

What is the function of the Instruction Decoder and Control Unit

Answer 11

• It decodes each instruction and under the supervision of a clock controls the external and internal units ensuring correct logical operation of the system.

Question 12

Give examples of information stored in microprocessors

Answer 12

a. the data to be used for computation
b. instructions and
c. computational results.

Question 13

What are the two classes of memory?

Answer 13

1. Random Access Memory (RAM) or Read/Write Memory (RWM)

2. Read-Only Memory (ROM)

Question 14

Discuss Bipolar v/s MOS Memories

Answer 14

• Basically there are two semiconductor technologies,
  namely, bipolar and MOS unipolar.
  • Mask ROMs and PROMs are available in both types whereas EAROMs and EPROMs are made with MOS technology only.
  • In general, bipolar devices (including memories) are faster and have higher drive capabilities.
  • On the other hand, MOS devices consume less space and power.

Question 15

Describe a peripheral interface

Answer 15

When one or more I/O devices (peripherals) are to be connected to a μP, an interface network for each device, called peripheral interface, is required.

Question 16

What are the functions of a peripheral interface?

Answer 16

• Buffering : Which is necessary to take care of incompatibility between the μP and the peripheral.
• Address Decoding : Which is required to select one of the several peripherals connected in the system.
• Command Decoding : Which is required for peripherals that perform actions other than data transfers.
• Timing and Control : All the above functions require timing and control.

Question 17

What are the two main categories for data exchanges that occur between a peripheral device and the μC

Answer 17

1. Programmed Data Transfer - A software routine residing in memory requests the peripheral device for data transfer to or from the μP.
2. Direct Memory Access (DMA) Transfer or Cycle Stealing Transfer - the data transfer is controlled by the
   peripheral device

Question 18

Give examples of hardware(IC Chips ) that can be used to build a custom interface

Answer 18

multiplexer, and demultiplexers, line drivers and
receivers, level translators and buffers a stable and monostable multivibrators, latches, gates, shift registers, and so on.

Question 19

What is a program and what is software

Answer 19

A sequence of instructions designed to perform a particular task in a computer is known as the program and a set of programs written for a computer-based system is called software for that system.

Question 20

Examples of software tools

Answer 20

Assembler, Compiler, Editor, System Monitor

Question 21

What does it mean to say that that the memory is 133MHz and the processor is 1.4 GHZ?

Answer 21

Saying a memory is 133Mhz means that the memory can be accessed at 133,000,000 cycles per second. The speed of the processor is 1, 400,000,000 cycles per second.