CL MEDIA (P) LTD. Edition : 2019 © PUBLISHER

Administrative and Production Offices

No part of this book may be reproduced in a retrieval system or transmitted, in any form or by any means, electronics, mechanical, photocopying, recording, scanning and or without the written permission of the publisher.

Published by : CL Media (P) Ltd. A-45, Mohan Cooperative Industrial Area, Near Mohan Estate Metro Station, New Delhi - 110044 Marketed by : G.K. Publications (P) Ltd.

ISBN

: 978-93-89573-29-9

Typeset by : CL Media DTP Unit

A-45, Mohan Cooperative Industrial Area, Near Mohan Estate Metro Station, New Delhi - 110044

For product information : ISBN-93-87444-84-3 Visit www.gkpublications.com or email to [email protected]

Contents 1. Computer Systems

1.1 – 1.14

2. Input and Output System

2.1 – 2.8

3. File Systems

3.1 – 3.8

4. Number System and Arithmetic

4.1 – 4.8

5. Programming Languages

5.1 – 5.12

6. C’ Programming

6.1 – 6.12

7. Memory Organisation

7.1 – 7.10

8. Database

8.1 – 8.16

9. Computer Network

9.1 – 9.10

10. Data Communication 11. CAD/CAM and Industrial Application

10.1 – 10.12 11.1 – 11.8

12. Internet

12.1 – 12.18

13. Microsoft Windows and MS Office

13.1 – 13.18

14. Computer Abbreviations and Glossary

14.1 – 14.5

1

C HAPTER PERSONAL COMPUTERS

Computer System

1. Desktop computers

they are external and connect to the back plate. The monitor is also connected to the back plate, except not (usually) directly to the motherboard, but to a connector in the graphics card.

2. Laptop or notebooks

Mass storage.

3. Personal Digital Assistants (PDAs)

It can be

4. Portable computers

(i) Hard disk

5. Tablet computers

(ii) Floppy drive or zip drive (both with media)

6. Wearable computers

(iii)Optical drive (CD or DVD)

Personal computers can be categorized by size and portability as :

Uses. Personal computers are normally operated by one user at a time to perform such general purpose tasks as word processing, Internet browsing, Internet faxing, e-mail and other digital messaging , multimedia playback, computer game play, computer programming, etc. The user of modern personal computer may have significant knowledge of the operating environment and application programs, but is not necessarily interested in programming not even able to write programs for the computer. Therefore, most software written primarily for personal computers tends to be designed with simplicity of use, or “user-friendliness” in mind. However, the software industry continuously provide a wide range of new products for use in personal computers, targeted at both the expert and the non-expert user. COMPUTER COMPONENTS 1. Computer case with power supply (usually sold together) 2. Motherboard 3. Processor with fan (usually sold together) 4. At least one memory card 5. Mass storage 6. Keyboard and mouse for input 7. Monitor for output The motherboard connects everthing together. The memory card(s), graphics card and processor are mounted directly onto the motherboard (the processor in a socket an the memory and graphics cards in an expansion slot). The mass storage is connected to it with cables. Same for keyboard and mouse, except that

The operating system (e.g., Microsoft Windows, Linux or many others) can be located on either of these, but typically it son one of the hard disks. Alive CD is also possible, but very slow and used for either installation of the OS or problem solving. A typical computer also has (i) Sound card (ii) Network card (iii)Modern and possibly router Common additions, connected on the outside (peripherals). Printer; Scanner; Webcam; Speakers; Microphone; Headset; Card reader; Gaming devices such as a joystick Several functions (implemented by chipsets) can be integrated into the motherboard, such as typically USB and network, but also graphics and sound. But even if these are present, a separate card can be added if what is available isn’t sufficient. The graphics and sound card can have a break out box to keep the analog parts away from the electromagnetic radiation inside the computer case. For really large amounts of data, a tape drive can be used or (extra) hard disks can be put together in an external case. These components can usually be put together with little knowledge, to build a computer. If something shouldn’t go somewhere, it usually doesn’t fit (this used to not always be the case in the past) and if it does fit it can usually do little harm. Most personal computers are standardized to the point that purchased software is expected to run with little or no customization for the particular computer. Many PCs are also user-upgradeable, especially desktop and workstation class computers. Devices such as main

1.2

Computer System

memory, mass storage, even the motherboard and central processing unit may be easily replaced by an end user. This upgradeability is, however, not idefinite due to rapid changes in the personal computer industry, A PC that was considered top-of-the-line five or six years prior may be impractical to upgrade due to changes in industry standards. Such a computer usually must be totally replaced once it’s no longer suitable for its purpose. This upgrade and replacement cycle is partially related to new releases of the primary mass-market operated system, which tends to drive the acquisition of new hardware and tends of obsolete previously serviceable hardware (see planned obsolescence). The hardware capabilities of personal computers can sometimes be extended by the addition of expansion cards connected via an expansion bus. Some standard peripheral buses often used for adding expansion cards in personal computers as of 2005 are PCI, AGP (a highspeed PCI bus dedicated to graphics adapters), and PCI Express. Most personal computers as of 2005 have multiple physical PCI expansion slots. Many also include an AGP bus and expansion slot or a PCI Express bus and one or more explansion slots, but few PCs contain both buses.

particular time. Main memory is much faster than mass storage devices like hard disks or optical discs, but is usually volatile, meaning it does not retain its contents (instructions or data) in the absence of power, and is much more expensive for a given capacity than is most mass storage. Main memory is generally not suitable for long-term or archival data storage.

Motherboard. The motherboard (or mainboard) is the primary circuit board within a personal computer. Many other components connect directly or indirectly to the motherboard. Motherboards usually contain one or more CPUs, supporting circuitry - usually integrated circuits (ICs) providing the interface between the CPU memory and input/output peripheral circuits, main memory, and facilities for initial setup of the computer immediately after being powered on (often called boot firmware or, in IBM PC compatible computers, a BIOS). In many portable and embedded personal computers, the motherboard houses nearly all of the PC’s core components. Often a motherboard will also contain one or more peripheral buses and physical connectors for expansion purposes. Sometimes a secondary daughter board is connected with the motherboard to provide further expandibility or to satisfy space constraints.

MICROPROCESSOR.

Main Memory. A PC’s main memory (i.e., its primary store) is fast storage that is directly accessible by the CPU, and is used to store the currently executing program and immidiately needed data. PCs use semiconductor Random Access Memory (RAM) of various kinds such as DRAM or SRAM as their primary storage. Which exact kind depends on cost/performance issues at any

Mass storage devices store programs and data even when the power is off; they do require power to perform read/write functions during usage. Although semiconductor flash memory has dropped in cost, the prevailing form of mass storage in personal computers is still the electromechanical hard disk. The disk drives use a sealed Head/Disk Assembly (HDA) which was first introduced by IBM’s “Winchester” disk system. The use of a sealed assembly allowed the use of the positive air pressure to drive out particles from the surface of the disk, which improves reliability. Video Card. The video card- otherwise called a graphics card, graphics adapter or video adapter - processors and renders the graphics output from the computer to the computer display, also called the Visual Display Unit (VDU), and is an essential part of the modern computer.

Memory Micro processor

I/O

A microprocessor is a multipurpose programmable logic device that reads binary instructions from a storage device called memory, accepts binary data as input and process data according to those instructions and provides results as output. A typical programmable machine can be represent with three components : microprocessor, memory, and I/O. These three components work together or interact with each other to perform a given task, thus they comprise a system HARDWARE. The physical components of this system are called hardware. SOFTWARE A set of instructions written for the microprocessor to perform a task is called a program and a group of programs is called software.

Computer System

APPLICATIONS. The microprocessor applications are classified primarily in two categories (i) In Re-programmable systems. Such as microcomputers, the microprocessor is used for computing and data processing. These systems, include general purpose microprocessor capable of handling large data. Mass storage device (disks), and peripherals such as I/O device (printer). (ii)Embedded system. In embedded systems, the microprocessor is part of a final product and is not available for reprogrammable to the end user. A copying machine is a typical example of an embedded system. The microprocessors used in these systems are generally categorised as (a) Microcontrollers that include all the components like microprocessor, memory and I/O. (b) Integrated microprocessor that include various devices such as timers and various types of I/O on a chip. (c) General purpose microprocessor with discrete components such as microprocessor, memory and I/O. Embedded systems can also be increased as products that use microprocessor to perform their operations they are called as microprocessor based products. e.g. washing machines, dish washers, automobile dashboard controls, traffic light controllers, and automatic testing instruments. BINARY DIGIT. The microprocessor operates in binary digits 0 and 1, also known as bits. Bit is an abbreviation for the term binary digit. Those digits are represented in terms of electrical voltages in the machine : generally 0 represents one voltage level and 1 represents another. The digits 0 and 1 are also synonyms with low and high respectively. Each microprocessor recognizes and processes a group of bits called the word and microprocessor are classified according to their word length. Memory. Memory is like the pages of a notebook with space for a fixed number of binary numbers on each line. However these pages are generally made of semiconductor material. Each line in 8 bit register that can store 8 bit binary bits, and several of these registers are arranged in a sequence called memory.

1.3

Input/Output. The user can enter instructions and data into memory through devices such as keyboard or simple switches. These devices are called input devices. The microprocessor reads instructions from the memory and processes the data according to those instructions. The result can be displayed by a device such as seven segment LED (light emitting diodes) or printed by a printer. These devices are called output devices. MICROPROCESSOR AS A CPU. The central processing unit (CPU) consists of the Arithmetic Logic Unit (ALU) and Control Unit (CU). The CPU contains various registers to store data, ALU to perform Arithmetic and logical, operations, instruction decoders, counters and control lines. The CPU reads instructions from the memory and perform the tasks specified. It communicates with input/output devices either to accept or to send data. These devices are also known as peripherals. The CPU is the primary and central player in communicating with devices such as memory, input and output. However, the timing of the communication process is controlled by the group of circuit called control unit. CPU on single chip called microprocessor. Arithmetic Logic Unit (ALU)

Control Unit

Input

Output

Memory

Fig. (a) Traditional block diagram of a computer

Input

Micro processor as CPU

Output

Memory

Fig. (b) Block diagram of a computer with the microprocessor as CPU

1.4

Computer System

1. bit microprocessor. The Intel 4004 was the first 4 bit programmable device that was primarily used in calculators. 2. bit microprocessor. The intel 8008 is 8 bit microprocessor, which was in turn superseded by the Intel 8080. Intel 8080 widely used in control applications, and small computers also were designed using the 8080 as the CPU. Within a few years after the emergence of the 8080, the Motorola 6800 and Zilog Z80 and Intel 8085 microprocessor were developed as improvements 3. 16 bit microprocessor. 8086/88 4. 32 bit microprocessor

e.g. These computers include such systems as Intel SDK85, SDK86, Motorola Evaluation kits, these are generally used to write and execute assembly language programs and to perform interfacing experiments 4. Single chip microcomputers (microcontrollers) These microcomputers are designed on a single chip, which typically includes a chip of 64 bytes of R/W memory from 4K to 2K bytes of ROM and several single lines to connect I/Os. These are complete microcomputers on a chip, they are also known as microcontrollers. These are used primarily for such functions as controlling appliances and traffic lights. e.g. Zilog Z8, Intel MCS51 and 96 series, and Motorola 68H C11.

80380/486 and Pentium 5. 64 bit microprocessor Motorola 68000 series MICROCOMPUTERS. Microcomputer is classified in four groups. 1. Personnel computers. These microcomputers are single user systems and being used for variety of purposes, such as payroll, business accounts, word processing, legal and medical record keeping, personnel finance and instructions. A typical configuration includes a 16 or 32 bit microprocessor, 2 to 4 MB (megabyte) of system memory, a video screen, a dot matrix printer. 2. Work stations. These are high performance cousins of the PC. They are used in engineering and scientific applications such as computer-aided design (CAD), computer aided engineering (CAE), and computeraided manufacturing (CAM), they generally include system memory larger than 200 MB, storage memory in giga bytes and high resolution screen. The work stations are designed around RISC processors. The RISC processors tend to be faster and more efficient than the processors used in personnel computer. 3. Single board microcomputers. These microcomputers are primarily used in college, laboratories and industries for instructional purposes or to evaluate the performance of a given microprocessor. They can also be part of some larger systems. Typically these microcomputers include 8 or 16 bit microprocessor.

COMPUTER LANGUAGES. Nibble. It is a group of four bits Mnemonic. A combination of letters to suggest the operation of an instruction. Compiler. A program that translates english like words of high language in the machine language of a computer. A complier reads a given program, called a source code and then translates the program into the machine language which is called an object code. Assembler. A computer program that translates an assembly language program from mnemonics to the binary machine code of a computer. Monitor program. A program that interprets the input from a keyboard and converts the input into its binary equivalent. COMPUTER SYSTEM. 8085 Programming Model. The 8085 programming model includes six registers, one accumulator and one flag register. It has two 16 bit register the stack pointer and the program counter. Registers. The 8085 has six general purpose registers to store 8 bit data. These are identical as B, C, D, E, H and L. They can be combined as Registers pairs BC, DE, and HL to perform some 16 bit operations. The programmer can use these registers to store or copy data into the registers by using data copy instructions.

Computer System

1.5 Accumulator A

(8)

B

(8)

C

(8)

D

(8)

E

(8)

H

(8)

L

(8)

Stack pointer

(SP)

(16)

Program counter

(PC)

(16)

Flag Register

Address Bus

Data Bus 8

Lines

Lines

Bidirectional

D7

D6

S

Z

D5

Unidirectional Fig. (a) Programming model

D4

D3

D2

AC

D1

D0

P

CY

Fig. (b) Flab Register

Accumulator. The Accumulator is an 8 bit register that is part of the arithmetic/logic unit (ALU). This register is used to store 8 bit data and to perform arithmetic/logic unit (ALU). This register is used to store 8-bit data and to perform arithmetic and logical operations. The result of an operation is stored in the accumulator. The accumulator is also identified as register A. FLAGS. The ALU includes five flip-flops, which are set or reset after an operation according to data conditions of the result in the accumulator and other registers. They are called zero (Z), carry (CY); sign (S), parity (P) and Auxiliary carry (AC) flags. The most commonly used flags are zero, carry, and sign. The microprocessor uses these flags to test data conditions. After an addition of two numbers, if the sum in the accumulator is larger than eight bits, the flip-flop used to indicate a carry called carry flag (CY) is set to one. When an arithmetic operation is zero the flip flop called the zero (Z) flag is set to one. The flags have critical importance in the decision making process of the microprocessor. The conditions (set or reset) of the flags are tested through software instructions.

that is why this is a 16-bit register. The microprocessor uses this register to sequence the execution of the instructions. The function of the program counter is to point to the memory addresses from which the next byte is to be fetched. When a byte (machine code) is being fetched, the program counter is incremented by one to point to the next memory location. STACK POINTER (SP). The stack pointer is also a 16 bit register used as memory pointer. It points to a memory location in R/ W memory, called the stack. The beginning of stack is defined by loading a 16-bit address in the stack pointer. OPCODE FORMAT. In the design of the 8085 microprocessor chip, all operations, registers and status flags are identified with a specific code. All internal registers are identified as follows : Code Registers

Code

Register pairs

000

B

00

BC

001

C

01

DE

010

D

10

HL

011

E

11

A F or S P

100

F

101

G

110

Reserved for Memory Related Operation

111

A

PROGRAM COUNTER (PC). This 16 bit register deals with sequencing the execution of instruction. This register is a memory pointer. Memory locations have 16 bit addresses, and

1.6

Computer System

INSTRUCTION CODES.

Immediate mode.

An instruction code is a group of bits that instruct the computer to perform a specific operation. It is usually divided into parts, each having its own particular interpretation. The most basic part of an instruction codes is its operation part.

The operand is specified in the instruction itself. In other words, an immediate mode instruction has an operand field rather than an address field. The operand field contains the actual operand to be used in conjunction with the operation specified in the instructions.

Operation Code. The operation code of an instruction is a group of bits that define such operations as add, subtract, multiply, shift and complement. The number of bits required for the operation code of an instruction depends on the total number of operations available in the computer. The operation code must consist of atleast n bits for a given 2n (or less) distinct operations. OP Code. What task to be performed, called the operation code (OPcode). Operand. When data to be operated on called the operand. The operand (or data) can be specified in various ways. It may include 8-bit or (16 bit) data, an internal register, a memory location, or 8 bit (or 16 bit) address. In some instructions, the operand is implicit. ADDRESSING MODES. The control unit of a computer is designed to go through an instruction cycle that is divided into three major phases.

Register mode. In this mode the operands are in registers, that reside within the CPU. The particular register is selected from a register field in the instruction. A K bit field can specify any one of 2k registers. Register indirect mode. In this mode the instruction specifies a register in the CPU, whose content gives the address of the operand in memory. The advantage of a register indirect mode instruction is that the address field of the instruction uses fewer bits to select a register than would have been required to specify a memory address directly, Auto Increment or Decrement mode. This is similar to register indirect mode except that the register is incremented or decremented after or before its value is used to access memory. When the address stored in the register refers to a table of data in memory, it is necessary to increment and decrement the registers after every access to the table Direct addressing mode.

(iii)Execute the instruction

In this mode the effective address is equal to the address part of the instruction. The operand resides in memory and its address is given directly by the address field of the instruction.

Implied mode.

Indirect addressing mode.

All register reference instructions that use an accumulator are implied mode instructions. Zero address instructions in a stack-organized computer are implied mode instructions since the operands are implied to be on top of the stack.

In this mode the address field of the instruction gives the address where the effective address is stored in memory.

(i) Fetch the instruction from memory (ii) Decode the instruction

Effective address = address part of instruction + content of CPU register

Computer System

1.7

EXERCISE 1. Which of the following is not used as secondary storage ? (a) Semiconductor memory (b) Magnetic disks

8. The register which keeps track of the execution of a program and which contains the memory address of the instruction currently being executed is called

(c) Magnetic drums

(a) index-register

(d) Magnetic tapes

(b) memory address register

2. Which of the following memory is capable of operating at electronics speed ? (a) Semiconductor memory (b) Magnetic disks

(c) program counter (d) instruction register 9. The register which holds the address of the location to or from which data are to be transferred is called

(c) Magnetic drums

(a) index register

(d) Magnetic tapes

(b) instruction register

3. Which of the following is responsible for co-ordinating various operations using timing signals ? (a) Arithmetic-logic-Unit (b) Control unit (c) Memory unit (d) Input/Output unit 4. The ALU of computer normally contains a number of high speed storage elements called (a) semiconductor memory (b) registers (c) hard disk (d) magnetic disk 5. Memories in which any location can be reached in a fixed (and short) amount of time after specifying its address is called

(c) memory address register (d) memory data register 10. The register which contains the data to be written into or readout of the addressed location is called (a) index register (b) memory address register (c) memory data register (d) program counter 11. A collection of wires that connects several devices is called (a) link

(b) bus

(c) bidirectional wires (d) cables 12. A memory bus in mainly used for communication between (a) processor and memory

(a) sequential-access memory

(b) processor and I/O devices

(b) random-access memory

(c) I/O devices and memory

(c) secondary memory

(d) input device and output device

(d) mass storage 6. Which of the following is the fastest ?

13. The input unit of a computer (a) feeds data to the CPU or memory

(a) CPU

(b) retrieves data from CPU

(b) magnetic tapes and disks

(c) directs all other units

(c) video terminal

(d) all of these

(d) sensors, mechanical controllers 7. The register which contains the instruction that is to executed is called

14. Which of the following is used as storage locations both in the ALU and the control section of a computer ?

(a) index-register

(a) Accumulator

(b) instruction register

(b) Register

(c) memory address register

(c) Adder

(d) memory data register

(d) Decoder

1.8

Computer System

15. Offline device is (a) a device which is not connected to CPU (b) a device which is connected to CPU (c) a direct access storage device

24. Which of the following registers is loaded with the contents of the memory location pointed by the PC ? (a) Memory Address Register (b) Memory Data Register

(d) an I/O device 16. A device or peripheral equipement which is not in direct communication with CPU of a computer is known as (a) on-line-device

(b) off-line-device

(c) channel

(d) intelligent terminal

17. A storage device used to compensate the differences in flow of data is called

(c) Instruction Register (c) Program counter 25. Registers which are partially visible to users and used to hold conditional codes (bits set by the CPU hardware as the result of operations), are called (a) PC (b) Memory Address Registers

(a) main storage

(b) auxiliary storage

(c) General purpose registers

(c) buffer

(d) core memory

(d) Flags

18. Which of the following registers holds the information before it goes to the decoder ? (a) Control register

(b) Data register

(c) Accumulator

(d) Address register

19. Which of the following is a set of general purpose internal registers ? (a) Stack

(b) Scratchpad

(c) Address register

(d) Status register

20. A single bus structure is primarily found in (a) main frames

(a) instruction execution (b) straight line sequencing (c) instruction fetch (d) random sequencing 27. One of the main feature that distinguish microprocessors from microcomputers is (a) words are usually larger in microprocessors (b) words are shorter in microprocessors

(b) super computers (c) high performance machines (d) mini-and micro-computers 21. In which addressing mode, the effective address of the operand is generated by adding a constant value to the contents of a register ? (a) Absolute mode

26. The process of fetching and executing instructions, one at a time, in the order of increasing addresses is called

(b) Indirect mode

(c) Immediate mode (d) Index mode 22. The unit of a computer system that executes program, communicates with and often controls the operation of other subsystems of the computer is called (a) CPU (b) Control Unit (c) I/O unit (d) peripheral unit 23. Which of the following registers is used to keep track of address of the memory location where the next instruction is located ?

(c) microprocessor does not contain I/O devices (d) computer are not fully integrated 28. Microprocessor can be used to make (a) computers

(b) digital systems

(c) calculators

(d) all of the above

29. In a generic microprocessor, instruction cycle time is (a) shorter than machine cycle time (b) larger than machine cycle time (c) exactly double the machine cycle time (d) exactly the same as the machine cycle time 30. What is the minimum number of operations required, for a microprocessor with 8 data pins, to read a 32- bit word ? (a) 1

(b) 2

(c) 4

(d) 8

31. The flow and timing of data to and from the microprocessor is regulated by

(a) Memory Address Register

(a) control pins

(b) Memory Data Register

(b) address pins

(c) Instruction Register

(c) data pins

(d) Program Counter

(d) power pins

Computer System

1.9

32. What type of control pins are needed in a microprocessor to regulate traffic on the bus, in order to prevent two devices from trying to use it at the same time ? (a) Bus control

(b) Interrupts

(c) Bus abitration

(d) Status

33. A microprocessor with 12 address lines is capable of addressing

39. Which of the following is not a register ? (a) Buffer (b) Stack (c) Program counter (d) Accumulator 40. The clock interrupt handle on a computer requires 2 msec per clock tick. The clock runs at 60Hz. What percent of the CPU is devoted to the clock?

(a) 1024 locations

(b) 2048 locations

(a) 1.2

(b) 7.5

(c) 4096 locations

(d) 64 K locations

(c) 12

(d) 18.5

34. The control unit of a microprocessor (a) stores data in the memory

41. Which of the following is the programmable internal timer ?

(b) accepts input data from a keyboard

(a) 8250

(b) 8251

(c) performs arithmetic / logic functions

(c) 8253

(d) 8275

42. Addressing capability of Intel 8086 / 88 is

(d) none of these 35. The data bus in 8080 A / 8085 microprocessor is a group of (a) eight bidirectional lines that are used to transfer 8 bits between the microprocessor and its I/O and memory.

(a) 64KB (b) 512KB (c) 2MB (d) 1MB 43. Efficient use of addressing modes

(b) eight lines used to transfer data among the register

(a) speeds up execution

(c) eight unidirectional lines that are used for I/ O devices.

(c) reduces the size of instructions

(d) sixteen bidirectional lines that are used for data transfer between the microprocessor and memory. 36. The stack pointer in the 8085 microprocessor is a (a) 16-bit register that point to stack memory locations (b) 16-bit accumulator (c) memory location in the stack (d) flag register used for the stack 37. How many address lines are needed to address each memory location in a 2048  4 memory chip?

(b) reduces the number of instructions (d) all of the above 44. Which of the following applications are best handled in ROM ? (a) Storage of protected passwords (b) Storage of temporary variables (c) Storage of the operating system (d) Storage for microprograms 45. Consider a computer with three types of instructions, each with the following opcode lengths and assuming opcodes occur at the front of each machine instruction : 6-bit opcode

(a) 10

(b) 11

8-bit opcode

(c) 8

(d) 12

12-bit opcode

38. Which of the following statements is true about the Program Counter (PC) ?

14-bit opcode

(a) It is a cell in ROM.

The number of possible commands that can be represented in the 6-bit opcode, is

(b) It is a register.

(a) 32

(b) 16

(c) During execution of the current instruction, its content changes.

(c) 8

(d) 4

(d) It counts the number of instructions executed in a program.

46. The minimum number of operands with any instruction is (a) 1

(b) 0

(c) 3

(d) 2

1.10

Computer System

47. Which technique is preferable for transferring a large amount of data to and from a memory in a short time ? (a) DMA (b) Interrupt-driven I/O (c) Programmed I/O

54. The addressing mode used in an instruction of the form ADD X,Y is (a) absolute

(b) immediate

(c) indirect

(d) index

55. The shifting of program from one location to another in the memory is called (a) relocation

(d) None of these 48. The CPU after receiving an interrupt from an I/O device (a) hands over control of address bus and data bus to the interrupting device (b) halts for a predetermined time (c) branches off to the interrupt service routine immediately (d) branches off to the interrupt service routine after completion of the current instruction 49. Index register in a microprocessor is used for (a) indirect addressing (b) pointing to the stack address (c) address modification (d) keeping track of the number of time a loop is executed 50. Pseudo-instruction are (a) instructions in any program that have no corresponding machine code instruction (b) instructions that are partially executed

(b) data collection (c) data transmission (d) DMA 56. A set of related programa is called (a) Script (c) Stacks 57. Accumulator is a (a) hardwired circuit (b) register (c) combinational circuit (d) finite state machine 58. Program Status Word (PSW) contains various (different) status of (a) CPU (b) ALU (c) program (d) registers 59. Microprogramming is designing of

(c) instructions for catching

(a) ALU

(d) assembler directives

(b) CPU

51. The sequency of events that happen during a typical operations (a) PC MAR Memory MDR IR (b) PC Memory MDR IR

(b) Arrays (d) Package

(c) ROM (d) Control Unit 60. When an interrupt occurs, CPU saves the value of———in a stack,

(c) PC Memory IR

(a) accumulator

(d) PC MAR Memory IR

(b) program status word (PSW) only

52. A byte addressable computer has a memory capacity of 2m Kbytes and an perform 2n operations. An instruction involving 3 operands and n operator needs a maximum of

(c) Instruction Address Counter (IAC)only (d) both PWS and IAC 61. Masking the interrupts means (a) disable all interrupts

(a) 3m bits

(b) 3m + n bits

(b) disable some interrupts

(c) m + n bits

(d) none of the above

(c) disable I/O devices interrupts

53. In the previous problem if the computer is word addressable with the word size being 8 bytes, then the answer will be

(d) disable power-failure interrupt 62. Bus Arbitration is

(a) 3m bits

(a) clearing the bus

(b) 3m + n bits

(b) latching information on the bus

(c) m + n bits

(c) deciding the controller of the bus

(d) none of these

(d) controlling the bus

Computer System

63. Auxiliary memory is (a) memory slot

1.11

71. Which of the following devices should get higher priority in assigning interrupts ?

(b) extended memory

(a) Hard Disk

(b) Printer

(c) secondary memory

(c) Keyboard

(d) Floppy disk

(d) cache memory 64. Control Memory Address Register is present in (a) ALU (b) Instruction Register Unit (c) Control Unit (d) Disk Control Interface Unit 65. Stack consists of (a) Register (b) RAM (c) ROM (d) CPU 66. Associative memory is a (a) pointer addressable memory (b) very cheap memory (c) content addressable memory (d) slow memory 67. Role of tag register in Associative Memory is

72. Which of the following addressing modes permits relocation without any change whatsoever in the code ? (a) Indirect addressing (b) Indexed addressing (c) Base register addressing (d) PC relative addressing 73. Which of the following addressing modes facilitates access to an operand whose location is defined relative to the beginning of the data structure in which it appears? (a) absolute

(b) immediate

(c) index

(d) indirect

74. In which addressing modes the contents of a register specified in the instructions are first decremented, and then these contents are used as the effective address of the operands? (a) Index addressing (b) Indirect addressing

(a) acting as buffer

(c) auto increment

(b) acting as mask register

(d) auto decrement

(c) to write onto Associative Memory (d) to read content of Associative Memory 68. A latch is commonly used to (a) interface input devices (b) interface output devices (c) interface memory (d) interface DMA 69. For the daisy chain scheme of connecting I/O devices, which of the following statement is true? (a) It gives non- Uniform priority. (b) It gives uniform priority to all devices. (c) It is only useful for connecting slow devices to a processor.

75. The Intel 8085 microprocessor enters into wait state after the recognition of (a) HOLD

(b) READY

(c) RESET IN

(d) INTR

76. The data lines of intel 8085 processor are multiplexed with (a) higher order address line (b) lower order address line (c) status line (d) None of the above 77. The number of clock cycles necessary to complete 1 fetch cycle in 8085 is (a) 3 or 4

(d) It requires a separate interrupt pin on the processor for each device.

(b) 4 or 5

70. Relative mode of addressing is most relevant to writing

(d) 3 or 5

(a) coroutines

(c) 4 or 6 78. Which can read data and convert them to a form that a computer can use?

(b) position-independent code

(a) Logic

(b) Storage

(c) shareable code

(c) Control

(d) Input device

(d) interrupt handlers