MCQs

What is the name of the single circuit board that provides the path through which the processor communicates with memory components and peripheral devices?
a. Motherboard b. Master board c. Circuit master d. Bus master

What small computers control the operation of peripheral devices?
a. Microprocessors b. Microcomputers c. Device controller d. Bus masters.

Which of the following is NOT a function of the control unit?
a. To read and interpret program instructions.
b. To monitor network connections
c. To direct the operation of internal processor components
d. To control the flow of programs and data in and out of RAM

The processor’s high-speed working storage areas that store only a few bytes are called?
a. Decoders b. Registers c. Units d. Modules

The program register contains the:
a. Instruction being executed
b. Location in RAM of the next instruction to be executed
c. Results of the arithmetic and logic unit.
d. Instruction that is being decoded

Which type of PROM is found on all new PCs, I/O devices, and storage devices and is easily altered by the user?
a. RIMM b. SIMM c. DIMM d. Flash

How is an instruction cycle measured?
a. Instruction time or l-time only
b. Calculation time or C-time only
c. Execution time or E-time only
d. The lotal of l-time and E-time

CISC means:
a. Completely integrated serial computer
b. Coded instruction set computer
c. Common interactive sequential computer
d. Complex instruction set computer

The ability of processors to execute another instruction before the current instruction is
completed is called:
a. Parallel processing b. Multiprocessing c. Pipelining d. Streamlining

The new USB 2.0 standard is times faster that the original USB standard.
a. 2 b. 10 c. 40 d. 100

Which bus is also called FireWire?
a. PCI local bus b. Universal Serial Bus (USB) c. 1394 Bus d. SCSI

What port transmits data via infrared light waves?
a. IrDA b. USB 2.0 c. 1394 d. Parallel

What percent of PCs uses an Intel processor?
a. 50 b. 75 c. 90

Which hardware components of computer are usually found inside of the systems unit?
a. Processor, main memory and monitor
b. Processor, main memory and secondary memory
c. First, second, and third memory
d. The keyboard, the disks, and the memory

Which of the following is driving force of a computer?
a. Computer clock b. Input device c. Output device d. Memory

Which of the following is the main component of the computer?
a. Memory b. output unit c. Input Unit d. CPU

The CPU is an example of:
a. Software b. Program c. Hardware d. Input unit

CPU stands for
a. Central Processing Unit
b. Central Product Unit
c. Computing Program Usage
d. Central Programming Unit

The arithmetic/logic unit performs the following actions:
a. Control computer operations
b. Perform arithmetic functions such as addition and subtraction etc.
c. Perform logical comparisons, such as equal to, greater than, less than
d. Both b and c

The CPU includes all of the following components except:
a. Primary storage b. ALU c. Control Unit d. Register

Which component of CPU decides which operations are to be performed by the CPU?
a. ALU b. Control unit c. Register d. None

Which component of CPU compares the contents of two pieces of data?
a. ALU b. Control Unit c. Memory d. None

Which of the following is not used for data storage?
a. Disk b. Control unit c. RAM d. Register

All of the following are performed by the control unit except:
a. Executing an instruction
b. Storing data into registers
c. Fetching an instruction from memory
d. Determining the meaning of an instruction

Which component of CPU interacts with primary memory?
a. ALU b.control unit c. central processor d. Bus

Magnetic memory is also called:
a. RAM b. DVD-ROM c. Cache Memory d. Disk Memory

RAM is:
a. Volatile b. Nonvolatile c. Slow d. permanent storage

A bus line consists of:
a. Registers b. Accumulators c. Parallel data path d. Computer clock

A set of electrical paths that transport data from one part of the computer to another is called:
a. Bus b. Monitors c. Computer clock d. None

A type of buses that are used to control the sequence of operations while program is
executed is called:
a. Data bus. b. control bus c. Address bus d. None

Additional data and programs not being used by the CPU are stored in:
a. Secondary Storage b. Input Units c. Output Units d. CPU

Step by step instructions that run the computer are called:
a. Hardware b. Documents c. CPU d. Software

When CPU executes an instruction, which of the following happens first
a. Data fetch b. Instruction fetch c. Instruction execute d. Interpret instruction

Which of the following change the sequence of program?
a. Change program instruction
b. Control Transfer instruction
c. Data Transfer instruction
d. Change Sequence instruction

The process of translating instructions into commands is called:
a. Fetching b. Decoding c. Executing d. Transferring

Computer operations are synchronized by:
a. CPU clock b. Input device c. output device d. RAM

The system clock:
a. Keeps the time of day.
b. Keeps the system’s processing time.
c. Determines how long data remains in memory.
d. Measures data transfer time.

The clock rate of a processor is measured in:
a. Kilobyte b. Megahertz c. Megabyte d. Kilohertz

The shortest period of time:
a. Millisecond b. Nanosecond c. Pico second d. Microsecond

MHz is an abbreviation for:
a. Megahertz b. Milli hertz c. Micro hertz d. None

Temporary storage area within in the CPU are called:
a. Registers b. Accumulator c. ROMs d. RAM

All of the following may be stored in registers except:
a. Program instructions b. Memory addresses c. Data d. CPU instruction set

Registers that collect the results of computation are called:
a. General purpose b. Main Storage c. Storage registers d. Accumulator

The size of the accumulator register is:
a. 1 to 4 bit b. 1 to 4 kB c.1 to 4 bytes d. 1 to 4 MB

The size of DI, SI, SP and BP stack control register is:
a. 2 bytes each b. 6 bytes each c. 4 bytes each d. 8 bytes each

Which is not a kind of register?
a. Flag b. Segment c. Accumulator d. Math coprocessor

How many events happen on a CPU while executing an instruction?
a. 5 b.4. c.3 d.6

Which of the following factors does not affect computer processing speed:
a. Register b. RAM c. Speed of system clock d. Keyboard size

The CPU consists of the following parts:
a. CU and Main Memory
b. Control Unit and ALU
c. Main Memory and storage
d. Operating system and application

The data that is input into the ALU must reside in:
a. Secondary storage b. Control unit c. RAM d. Registers

Which of the following is not used for data storage?
a. Disk b. the control unit c. RAM d. Registers

Random access memory is located in:
a. Registers on the CPU
b. a chip near the CPU
c. Magnetic devices external to the computer
d. Bus lines on a microprocessor

Large amounts of memory can be stored least expensively in:
a. RAM. b. Registers. c Secondary storage. d. Primary storage.

A program’s instructions are stored in primary memory:
a. As long as a particular instruction is being processed in the ALU.
b. As long as the program is installed on the computer.
c. As long as the program is executing on the system.
d. As long as the user is interacting with the program.

The term used to describe the steps of fetching decoding, executing and storing the results of program instructions is:
a. Processing. b. Machine cycle. c. Instruction setting. d. I-time.

Machine cycle refer to:
a. l-time b. E-time c. Both l-time and E-time d. Neither I-time nor E-time.

Which of the following actions is done during the I-time of the machine cycle?
a. Decoding the instruction
b. Fetching the data to be processed by the instruction
c. Executing the instruction
d. Storing the results of the instruction

The unit of electronic circuitry that represents a single bit is called a
a. Chip b. Motherboard. c. Transistor. d. Register.

The following are all Intel chips or Intel-like chips except:
a. Xeon b. Celeron c. Cyrix d. Power PC

Which of the following is a volatile form of memory?
a. RISC b. Semiconductor RAM c. Flash RAM d. Programmable ROM

Which of the following can be used for permanent storage of changeable data?
a. Cache b. Semiconductor RAM c. Flash RAM d. Programmable ROM

Which of the following is the correct sequence of slowest-to-fastest RAM technologies?
a. SRAM – SDRAM – DRAM – RDRAM
b. DRAM -SDRAM – RDRAM – SRAM
c. SDRAM – RDRAM – DDRAM-SRAM
d. DRAM – SRAM – RDRAM – SDRAM

Which form of RAM utilizes battery power to retain information while computer is off?
a. DRAM b. SRAM c. L2 Cached. d. CMOS RAM

Which of the following is the most likely use for static RAM technology?
a. Primary memory b. Secondary storage c. Cache memory d. Registers

Expansion slots connect interface cards to:
a. Ports. b. Peripheral devices. c. Motherboard. d. System bus.

A port provides an interface between:
a. Expansion board and a peripheral device.
b. Adaptor card and the motherboard.
c. The CPU and Ll cache.
d. DRAM and SRAM.

Which is the correct correspondence of cycle time and cycle speed?
a. Picosecond – gigahertz
b. Millisecond-megahertz
c. Nanosecond – kilohertz
d. Nanosecond – gigahertz

Which of the following storage areas are kept within the CPU?
a. DRAM b. L1 Cache c. L2 Cache d. MIP RAM

Which of the following technologies pertain to the size of a CPU’s instruction set?
a. SRAM b. SIMM c. CRISC d. ISA

The ability to execute one instruction while the next is being fetched is made possible via:
a. Multiprogramming. b. Pipelining. c. Supercomputing d.CISC.

Which of the following involves the use of multiple processors in a single computer?
a. Pipeline processing
b. RISC processing
c. Parallel processing
d. Microprocessing

Built-in vocabulary of instructions that the processor can execute on a given computer is called:
a. Language b. Instruction set c. Chip size d. High-level language

The processors determines how individual components of the processor are put together on a chip.
a. Architecture b. Density c. Power distribution d. Both a and c

A computer processor with a smaller instruction set is sometimes classified as:
a. CISC b. RISC C. CIŞT d . CISR

A computer processor with a larger instruction set is sometimes classified as:
a. CISC b. RISE c. CIST d. CISR

The difference between a RISC and a CISC is:
a. RISC is faster b. RISC is smaller c. CISC is larger d. all of the above

The difference between RISC and CISC is:
a. RISC is slower b. CISC is smaller c. CISC is slower d. both b&c

Older Macintosh systems used processors developed and manufactured primarily by:
a. IBM b. Motorola c. Intel d. AMD

Newer Macintosh systems use processors developed and manufactured primarily by:
a. IBM b. Motorola c. Intel d. AMD

Most PCs and Macintoshes use processors of what size?
a.128-bits b. 64-bits c. 32-bits d. 16-bits

Some embedded and special-purpose computer still use processors of what size?
a. 64-bits .c. 16-bits c. 8-bits d. Both cand d

The term primary Storage is used to refer to:
a. Memory b.Таре c. Disk d. Both a and c

The most common type of primary storage to:
a. ROM b. EPROM c. RAM d. DOS

The acronym RAM stands for:
a. Readily available memory
b. read and more memory
c. Random access memory
d. remember all memory

An inherent characteristic of RAM is that it is:
a. Read only b. Writes only c. Nonvolatile d. Volatik

The acronym ROM stands for
a. Recursive online memory
b. Rapid online memory
c. Random only memory
d. None of above

An inherent characteristic of ROM is that it is:
a. Read only c. Volatile d. Nonvolatile d. Both band d

The difference between ROM and RAM is a:
a. ROM chips are larger
b. ROM is nonvolatile
c. ROM is read only
d. both cand d are correct

The type of memory used to store the date and calendar in a PC is called:
a. MODS b. RAM c. ROM d. CMOS

Nonvolatile RAM used in cell phones and pagers is stored in what kind of memory chips?
a. Zip b. Flash c. Laser d. Synchronized

For Macintosh computers, CMOS RAM is called:
a. Parameter RAM. b. Flash memory c. EPROM d. PROM

One big reason flash memory is NOT used as primary storage in personal computers is its:
a. Limited availability b. Inability to be written to c. Size d. cost

Access time for most memory is __ than access time for disk.
a. Bigger b. Longer C. Słower d. Faster

Access time for most memory is measured in:
a. Microseconds . b. Milliseconds c. Nanoseconds d. Megahertz

32-bit bus is ___than a 16-bit bus
a. Wider b. Longer c. Faster. d. Both a and c

Cards or boards used to connect additional devices to computer are connected to
motherboard via:
a. Expansion slots b. Links c. Bays d. Cornectors

A port on the computer may be connected to:
a. Expansion card b. CPU c. Motherboard d. Both a and b

Users can customize their computers by inserting special-purpose circuit boards into :
a. Ports b. Houses c. Slots d. PC cards

The external devices that are connected to a computer system are known as:
a. Expansion card b. Peripherals c. Buses d. Slots

How many separate on/off switches would be required in order to represent all the possible characters of the ASCII character code?
a. 10 b. 256 c. 8 d. 64

How many separate on/off switches would be required in order to represent all the possible
characters of the Unicode character code?
a. 10 b. 256 c. 8 d. 16

The EBCIDIC representation of the word hello takes:
a. 5 bytes b. 256 bits. c. 5 bits. d. 10 words.

The Unicode representation of the word hello takes:
a. 5 bytes. b. 256 bits. c. 5 bits d. 10 bytes

The smallest unit of information in the computer is a:
a. Character b. word c. bit d. byte

A bit can represent how many different values?
a. 0 b. 1 c. 2 d. 3

The meaning of the value of a bit is:
a. on or off b. one or zero c. yes or n d. all of the above

A binary message can be sent using:
a. One bit b. two bits c. Three bits d. four bits

A byte is _ bit(s)
a. 1 b. 2 c.4 d. 8

The most widely used code for representing characters in computers.is:
a. ASCI b. BCD c. EBCDIC. d. ASCHI

The ASCII coding system can provide _ different representations.
a. 2 b.4. c. 16 d. 256

A group of bits can represent
a. Characters b. colors c. Sounds d. all of the above

Combinations of bits are used to represent:
a. Data. b. The CPU. c. Programs. d. Both a and care correct

Fill in the Blanks

1. ______component of the CPU is responsible for interacting with primary memory. Control unit
2. ______ component of the CPU is responsible for comparing the contents of two pieces of data. ALU
3. ______ operator is used to tests for equality or inequality of two data values. Relational
4. A true/false value is the result of a ______ operation. Logical
5. During a calculation, the data that is input into the ALU resides in temporary storage locations called ______. Registers
6. The______involves the following steps: fetching, decoding, executing, and storing. Machine cycle
7. The ______contains all the machine commands that a CPU can understand and perform. Instruction set
8. The purpose of the ______ is to synchronize the computer operations of the CPU and RAM. System clock
9. The control unit knows where to look in memory for data or instruction because each data item in memory is identified by a specific ______. Address
10. A ______consists of eight bits. Byte
11. The word gigahertz means a billion machine ______. Cycles
12. Each character in a Unicode representation takes two ______ of storage space. Bytes
13. A transistor represents a single ______ of data. Bit
14. ______storage is lost when the electrical current is turned off. Volatile
15. ______ RAM utilizes battery power to retain information while the computer is shut off. CMOS
16. SRAM technology is used mostly for L2 ______ memory. Cache
17. The term ______ refers to the number of bits that can be transmitted from memory to the CPU in one fetch. Bus width
18. The system bus width is normally the same as a CPU’s ______. Word size
19. Interface cards are connected to peripheral devices via ______. Expansion slots (or ports)
20. ______cache is contained within the CPU. Expansion slots
21. ______technology minimizes the number of CPU instructions in a system’s instruction set. RISC
22. ______provides the ability for one instruction to execute while the next is being fetched. Pipelining
23. The chips of a computer are located on the ______. Motherboard
24. A ______is a set of electronic paths that transfer electrical signals between different chips. bus
25. A ______port transmits one bit at a time. Serial
26. A ______port transmits multiple bits at a time. Parallel

True / False

1. The circuit board on which the processor and other chips are placed is called the master board. F
2. The CPU is a peripheral device. F
3. Software written for a Macintosh computer will run on an IBM-compatible computer. F
4. Backward compatible means that older processors can process instructions handled by newer processors. F
5. Clock speed and architecture both contribute to how fast a computer can process. T
6. Clock speed is measured in megahertz. T
7. Word size is the number of bits a computer can process at one time. T
8. The arithmetic logic unit takes the instruction read by the prefetcher and translates it into a form suitable for the CPU’s internal processing. F
9. Execution of instructions is performed by the arithmetic logic unit (ALU). T
10. CISC is using a smaller instruction set to achieve faster processing. F
11. A series of processors that are compatible are called CISC. F
12. Research has shown that RISC processors are slower and less efficient than CISC processors. F
13. Reduced instruction set computing system uses fewer instructions to achieve faster processing. T
14. RISC is using parallel processing with the inherent risk that it will fail. F
15. One acceptable way of increasing computer processing speed is to use multiple processors. T
16. The most common type of primary storage is ROM. F
17. The most common type of primary storage is RAM. T
18. ROM contains start-up instructions. T
19. Volatile memory permanently stores information. F
20. The type of memory used to store the date and calendar is ROM. F
21. RAM is generally nonvolatile. F
22. ROM is nonvolatile. T
23. CMOS is used to store commonly used programs. F
24. Information travels between components on a bus. T
25. A port may be connected to the motherboard. T
26. Flash memory is used in cell phones and pagers. T
27. Access time for memory is generally faster than access time for disk. T
28. A PC card is credit card sized and may contain memory or miniature peripherals. T

Bays

Bay is an open area inside the system unit to install additional equipment. Bays are also called drive bays. Two types of bays are as follows:

External or Exposed Drive Bay: It is used to access the drive from outside the system unit. Some examples of external drive bays are a floppy disk drive, CD drive, DVD drive and Zip drive.

Internal or Hidden Drive Bay: It is hidden inside the system unit. An example of an internal drive bay is hard disk drive.

Power Supply

The power supply of a computer is a simple electrical system. It is used to supply correct voltage to different components of computer. It takes 240 or 110 AC voltages as input. It converts AC voltage into 3V, 6V, 12V and 24V of Direct Current (DC).

Different devices work with different voltages. Power supply detects the amount of voltage that a device requires. It supplies correct amount of voltage to different devices.

Factors Affecting Processing Speed

Following are some important factors that affect that processing speed of a computer:

1. Registers
2. RAM
3. System Clock
4. Buses
5. Cache Memory

1. Registers

Register is a small, high-speed memory inside a CPU. CPU contains a number of registers. Registers store data and instructions while the CPU processes them. The size of the registers determines the amount of data with which the computer can work at one time. It is also called word size.

The size of registers is in bytes. A register can be of one, two, four or eight bytes. Computers with 32-bit registers means the CPU can process four bytes of data at one time. Bigger size of register increases the performance of computer.

2. RAM

Amount of RAM directly affects the processing speed of the computer. Bigger amount of RAM means that more program instructions and data can be stored in memory. If a computer does not have enough memory to run a program, it must move data between RAM and the hard disk frequently. This process is called swapping that can greatly slow a computer’s performance.

3. System Clock

System clock is an electronic component. It generates electric signals at a fast speed. The time required to execule a single instruction is called clock speed. Clock speed lells us how much time a CPU takes to execute each instruction. CPU takes from 1 to 6 clock ticks to execute one instruction.

Clock speed is measured as cycles per second. Its unit is Hertz (Hz). If a computer has a clock speed of 300 MHz, its system clock ticks 300 million times every second. A faster clock can execute more instructions each second.

4. Buses

A bus is a path between the components of a computer. Data and instructions travel along these paths. The bus width determines how many bits can be transmitted between the CPU and other devices. Bus width also affects the performance of the computer. A higher bus width means that the user can carry more data. It increases the performance of computer.

5. Cache Memory

A cache (pronounced “cash”) is high-speed memory that holds the most recent data and instructions that have been loaded by the CPU It is designed to speed up the transfer of data and instructions Cache is located directly on the CPU or between the CPU and RAM It is faster than RAM.

The data and instructions are retrieved from RAM when CPU uses them for first time. A copy of that data or instructions is stored in cache. The next time the CPU needs that data or instructions, it first looks in cache. If the required data is found there, it is retrieved from cache memory instead of main memory. It speeds up the working of CPU. The amount of cache memory has a tremendous impact on the computer’s speed.

Buses are electrical paths or lines inside computer. These buses are used to carry electrical signals between different components of computer. One line of wire can carry one bit at a time.

The capacity of computer bus depends on the number of data lines it contains. Thus an 8-bit bus can carry 8 bits of data from one component to the other simultaneously. The amount of data that a bus can be carry at one time is called bus width. CPU communicates with other components of computer through buses.

Typically, computer bus consists of 40 to 150 electric wire lines running parallel to each other. Different types of buses are as follows:

1. Data Bus

The electrical path through which data is transferred between components of computer is called dala bus. The data bus typically consists of 8, 16, 32 or 64 separate lines.
The data bus lines are bi-directional. It means that the CPU can:

• Read data from memory using these lines.
• Write data to memory locations using these lines.

Different devices such as keyboard, memory and mouse work with data bus.

2. Address Bus

Many components are connected to one another through buses. Each component is assigned a unique ID. This ID is called the address of that component. If a component wants to communicate with another component, it uses address bus to specify the address of that component.

The address bus is also used to designate the source or destination of data on the data bus. The address bus typically consists of 8, 16, or 32 separate lines. The number of address fines determines the number of memory locations that CPU can address.

3. Control Bus

Control bus is used to transmit different commands from one component to another component. For example, if CPU wants to read data from main memory, it uses control bus to send the memory read command to the main memory of the computer.

The control bus is also used to transmit control signals like ACKS (Acknowledgement signals). Suppose that CPU gives a command to the main memory to write data. The memory sends the acknowledgment signal to the CPU after writing the data successfully. CPU receives the signal and then moves to perform some other action.

Some common commands are as follows:

4. Expansion Bus

Some devices connect to a port on a card which is ‘inserted into an expansion slot. This expansion slot connects to the expansion bus. The expansion bus allows the processor to communicate with the peripheral devices attached to the card.

Different types of expansion buses are as follows:

1. ISA Bus

ISA stands for Industry Standard Architecture. It is the most common and slowest expansion bus. Mouse, modem card, sound card and low-speed network interface card are connected to ISA bus directly or through ISA bus expansion slot.

2. Local Bus

It is a high-speed expansion bus. It connects higher speed devices like hard disk. VESA local bus is the first standard local bus. It was used for video cards. The current local bus standard is PCI bus. PCI stands for Peripheral Component Interconnect. It is more versatile than VESA. Video cards, sound cards, SCSI cards and high-speed interface cards are inserted into PCI bus expansion slot.

3. AGP Bus

AGP stands for Accelerated Graphics Port. It is designed by Intel to improve the speed of 3-D graphics and video transmit. It provides a faster-dedicated interface between the video card and memory.

4. USB

USB stands for Universal Serial Bus. It eliminates the need to install cards into expansion slots. Many USB devices can be attached to computer with single USB port.

5. PC Card Bus

It is designed for PC Card. It transmits data between PC Card bus and PCI bus.

A port is an interface or point of attachment. It is used to connect peripheral devices with computer such as printers, keyboards or mouse. Ports have different types of connectors. A connector joins a cable to a device. One end of the cable is attached to the connector on the system unit and the other end is attached to the connector on the peripheral device. Different genders of connectors are as follows:

Male Connectors: It has one or more exposed pins like the end of an electrical cord.

Female Connector: It has matching holes to accept the pins on a male connector like an electrical wall outlet.

Gender changer is a device that is used to join two connectors of same gender i.e. two male connectors or two female connectors.

Different types of ports are as follows:

1. Serial Ports

A serial port is used to connect devices to the system unit. A serial port transmits data one bit at a time. It is usually used to connect devices that do not require fast data transmission like mouse and keyboard etc.

2. Parallel Ports

Parallel port is used to connect devices that transfer many bits at a time. Printers connect to computer using a parallel port.

3. Universal Serial Bus Port

Universal serial bus port (USB) can connect up to 127 different peripheral devices with a single connector type. Many computers have one or two USB ports. Multiple devices can be attached to USB port through daisy chain. It means that the first device is attached to the USB port of the computer, second USB device connects to the first USB device, the third USB device connects to the second USB device and so on.

An alternate to daisy chain is USB hub. USB hub plugs into the USB port on the system unit. It contains multiple USB ports used to connect many USB devices.

4. Special-Purpose Ports

Some special-purpose ports are as follows:

1. 1394 Port

This port is also called FireWire port. It can connect multiple types of devices that require faster data transmission speeds like digital video cameras, digital VCR, color printers, scanners etc. It can connect up to 63 devices together.

2. MIDI Port

MIDI stands for musical instrument digital interface. MIDI port connects the system unit to a musical instrument like an electronic keyboard. A system unit with MIDI port can record sounds created by a synthesizer and then process these sounds. Synthesizer is peripheral or chip that creates sound from digital instructions.

3. SCSI Port

SCSI stands for small computer system interface. It is a special high-speed parallel port to attach SCSI peripheral devices like disk drives and printers. It can connect up to 15 devices using a daisy chain.

4. IrDA Port

IrDA stands for Infrared Data Association. It is also called Fast Infrared (FIR). A wireless device can transmit signals to a computer with IrDA port. Different devices use IrDA port like keyboard, mouse, printers, digital cameras etc. These devices use a high-speed IrDA port.

5. Bluetooth Port

Bluetooth port is an alternative of IrDA port. It uses radio waves to transmit data between two devices. Bluetooth-enabled devices can communicate with one another without aligned to one another. The USB port or serial port can be converted into Bluetooth port by using Bluetooth wireless port adapter.

PC card is a thin credit card size device. It is used to add memory, disk drives, sound, fax/modem, communications and other capabilities to a mobile computer like laptop. All PC Cards follows the standard developed by PCMCIA. It stands for Personal Computer Memory Card International Association.

Types of PC Cards

Three types of PC Cards are as follows:

Type I Card: It adds memory capabilities to the computer.

Type II Card: It contains communication devices such as modem.

Type In Card: It deals with the devices like hard disk. It is the thickest card.

PC Card and flash memory cards can be attached to the computer without opening the system unit and restarting the computer. The operating system automatically detects the PC Card and flash memory card as it is attached to the system. This feature is called hot plugging or hot swapping. This allows the user to add and remove devices while the computer is running.

Expansion slot is a socket that is mounted on a motherboard to insert circuit board. Different circuit boards are inserted into the motherboard to add new devices and enhance capabilities to the computer. Some examples are memory chips, sound devices, modems or graphics card etc. A circuit board is identified by different terms like card, expansion card, expansion board, adapter card, interface card, add-in and add-on etc.

Some cards contain built-in feature or device like modem card and graphics card. Some cards are attached to a device outside the system unit like scanner etc.

Types of Expansion Cards

Different types of expansion cards are as follows:

Video Card: It is also called video adapter or graphics card. It converts computer output into a video signal and sends it to the monitor to display.

Sound Card: It enhances the sound-generating capabilities of a computer. It allows sound to be input through microphone and output through speakers.

Network Interface Card (NIC): It is also called network card. It is a communication device that allows a computer to communicate via a network.

Modem Card: It is also called an internal modem. It is a communication device that enables computer to communicate via telephone lines or other means.

Cache Memory

A cache (pronounced “cash”) is a small and very fast memory. It is designed to speed up the transfer of data and instructions. It is faster than RAM. The data and instructions that are most recently or most frequently used by CPU are stored in cache.

The data and instructions are retrieved from RAM when CPU uses them for first time. A copy of that data or instructions is stored in cache. The next time the CPU needs that data or instructions, it first looks in cache. If the required data is found there, it is retrieved from cache memory instead of main memory. It speeds up the working of CPU.

Types of Cache Memory

Different types of cache memory are as follows:

Level 1 (L1) Cache: It is also called primary or internal cache. It is built directly into
the processor chip. It has small capacity from 8 KB to 128 KB.

Level 2 (L2) Cache: It is slower than L1 cache. Its size is large i.e. from 64KB to 4MB. New processors contain advanced transfer cache on processor chip that is a type of
L2 cache. The common size of this cache is 256 KB.

Level 3 (L3) Caches: This cache is separate from processor chip on the motherboard. It exists on computer that use L2 advanced transfer cache.

Flash Memory

Flash memory is also called flash ROM or flash RAM. It is a type of nonvolatile memory. It can be erased electronically and reprogrammed. Many computer are using flash BIOS, Flash BIOS can be updated easily if required.

Flash memory chip stores data on handheld computers like cellular phones, digital cameras etc. Another type of flash memory is Flash memory cards that stores flash memory on a removable device instead of chip.

CMOS

CMOS stands for complementary metal-oxide-semiconductor. It stores configuration information of computer. The information include the type of disk drivers, keyboard and monitor, current date & time and other startup information required during booting process.

CMOS chip uses battery power to retain information even when the computer is turned off. The information in CMOS can be changed.

Memory Access Times

The amount of time required by the processor to read data, instructions and information from memory is called access time. Access time is defined by different types of terminologies that are as follows:

• Millisecond: It is one thousandth of a second. It is denoted by ms.
• Microsecond: It is one millionth of a second. It is denoted by us.
• Nanosecond: It is one billionth of a second. It is denoted by ns.
• Picosecond: It is one trillionth of a second. It is denoted by ps.
• Megahertz: It can be converted into nanoseconds by dividing it into 1 billion ns. It is denoted by MHz.

Memory Module

RAM is mounted on a small circuit board called memory module. The memory module is mounted on motherboard. Three types of memory modules are as follows:

SIMM – SIMM stands for single inline memory module. In this module, the pins on opposite sides of the circuit board connect together to form a single set of contacts.

DIMM – DIMM stands for double inline memory module. In this module, the pins on opposite sides of the circuit board do not connect and form two set of contacts.

RIMM – RIMM stands for Rambus inline memory module. It houses SDRAM chips.

Read-Only Memory (ROM)

ROM stands for read only memory. The instructions in ROM prepare the computer for use. These instructions can only be read but cannot be changed or deleted. It is not possible to write new information or instructions into the ROM.

ROM stores data and instructions permanently. When the power is switched off, the instructions stored in ROM are not lost. Therefore ROM is called non-volatile memory.

The information in ROM is stored by the manufacturer. When the computer is switched on, the instructions in the ROM are automatically loaded into the memory of the computer.

Different types of ROM are as follows:

1. PROM

PROM stands for Programmable Read Only Memory. This form of ROM is initially blank. The user or manufacturer can wrile data on it using special devices. The user can write data and instructions on it only once. If there is any error in writing the instructions, the error cannot be removed from PROM. The chip becomes unusable. It is used to store the programs or data developed by user.

2. EPROM

EPROM stands for Erasable Programmable Read Only Memory. User can erase instructions or data stored in EPROM chip by exposing the chip to ultraviolet light and write new program.

3. EEPROM

EEPROM stands for Electronically Erasable Programmable Read Only Memory. In this memory, user can erase and write instructions with the help of electrical pulses. If there is any error in writing the instructions, the user can erase the contents electrically.

Difference between RAM & ROM

The difference between RAM and ROM is as follows:

Difference between PROM and EPROM

The difference between PROM and EPROM is as follows:

Memory

Data and instructions are stored in memory to be executed. This memory is a temporary storage unit for data, instructions, and information. It is also called primary storage. It consists of one or more chips on the motherboard. The memory stores the following three items:

1. Operating system and other system software to control the use of computer system.
2. Application programs to perform specific tasks.
3. Data to be processed by application programs.

The instructions and data is stored in memory as bytes during execution. Each byte in the memory has its unique address that identifies its location. There are two types of memory in the computer that are as follows:

Volatile Memory – Volatile memory loses its contents when the computer is turned off.
Non-Volatile Memory – It does not lose its contents when computer is turned off.

RAM

RAM stands for Random Access Memory. It is also called main memory or Direct Access Memory. Random access means that each individual byte in the entire memory is directly accessible. A program must be loaded into RAM before execution.

RAM is temporary memory. When the power is turned off, the information in this memory is lost. Thus it is called volatile memory.

RAM plays very important role in the processing speed of a computer. A bigger RAM size provides larger amount of space for processing. So the processing speed is increased. CPU can read data from RAM and write data to RAM. That is why RAM is also known as read/write memory. It is used to store data and instruction while it is being executed,

There are two types of RAM:

1. Static RAM

SRAM stands for Static Random Access Memory. The memory cells are made from digital gates. Each cell can store its value without any need to refresh the data as long as the power is available.

SRAM is more expensive. It does not need to be power-refreshed, CPU does not wait to access data. That is why it is faster. It utilizes more power than DRAM. It is normally used to build a very fast memory known as cache memory.

2. Dynamic RAM

DRAM stands for Dynamic Random Access Memory. It is a type of memory that is used in most computers. It is the least expensive kind of RAM.

DRAM requires an electric current to maintain its electrical state. The electrical charge of DRAM decreases with time that may result in loss of data. DRAM is recharged or refreshed again and again to maintain its data. The processor cannot access the data of DRAM when it is being refreshed. That is why it is slow.

Differences between SRAM and DRAM

The difference between SRAM and DRAM is as follows: