Comphar Midterm Lec1 (Memory Basic)

7/31/2019 Comphar Midterm Lec1 (Memory Basic)

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MEMORY


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MEMORY

The workspace for the computers processor.

A temporary storage area where theprograms and data being operated on by the

processor must reside.


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MEMORY CAPACITY

BitShort for binary digit (0s and 1s), the only data that a

CPU can process.

ByteAn 8-bit string of data, needed to represent any one

alphanumeric character or simple mathematical

operation.


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HIERARCHY OF MEMORY CAPACITY

Kilobyte (KB): approximately one thousand bytes.

Megabyte (MB): approximately one million bytes(1, 048, 576 bytes, or 1,024 x 1, 024)

Gigabyte (GB): actually 1,073,741,824 bytes(1,024 x 1,024 x 1,024 bytes)


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HIERARCHY OF MEMORY CAPACITY

Terabyte: one trillion bytes.

Petabyte: Approximately 105 bytes.

Exabyte: Approximately 108 bytes.


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COMPUTER MEMORY

Two basic categories of computer memory

Primary storage - Stores small amounts of data andinformation that will be immediately used by the CPU

Secondary storage - Stores much larger amountsof data and information (an entire software program,

for example for extended periods of time)


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PRIMARY STORAGE or MAIN

MEMORY - Stores 3 types of information forvery brief periods of time:

Data to be processed by the CPU.

Instructions for the CPU as to how to

process the data.

Operating system programs that manage

various aspects of the computers

operation.


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MAIN TYPES OF PRIMARY STORAGE

Register

Random access memory (RAM)

Cache memory

Read-only Memory

Flash memory


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REGISTERS

Part of the CPU with the least capacity,

storing extremely limited amounts of

instructions and data only immediately beforeand after processing.


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RAM (Random Access Memory)

Main memory is called RAM because you can

randomly (as opposed to sequentially) access

any location in memory.

The part of primary storage that holds a

software program and small amounts of data

when they are brought from the secondarystorage.


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Cache memory

A type of primary storage where the computer

can temporarily store blocks of data used more

often.

Extremely fast memory that is built into a

computers CPU, or located next to it on a

separate chip.

The CPU uses cache memory to store

instructions that are repeatedly required to run

programs, improving overall system speed.


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Cache memory

The advantage of cache memory is that the

CPU does not have to use the motherboards

system bus for data transfer.

Whenever data must be passed through the

system bus, the data transfer speed slows to

the motherboards capability.


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ROM (Read-only memory)

type of memory that can permanently or

semi permanently hold data.

It is called read-only because it is either

impossible or difficult to write to.


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ROM also is often referred to as nonvolatile

memorybecause any data stored in ROM

remains there, even if the power is turned off.

ROM is an ideal place to put the PCs

startup instructions that is the, the software

that boots the system. (OS)


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Note: ROM and RAM are not opposites, as some

people seem to believe. Both are simply types of

memory. In fact, ROM could be classified as

technically a subset of the systems RAM. In otherwords, a portion of the systems random access

memory address space is mapped into one or

more ROM chips. This is necessary to contain the

software that enables the PC to boot up; otherwise,

the processor would have no program in memory

to execute when it was powered on.


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FLASH MEMORY

A form of rewritable read-only memory that is

compact, portable, and requires little energy.

Flash memory is a type of constantly-powerednonvolatile memory that can be erased and

reprogrammed in units of memory called

blocks. (memory blocks)


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FLASH MEMORY

Flash memory is often used to hold control

code such as the basic input/output system

(BIOS) in a personal computer. When BIOS

needs to be changed (rewritten), the flashmemory can be written to in block (rather than

byte) sizes, making it easy to update.


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SECONDARY STORAGE

Memory capacity that can store very large

amounts of data for extended periods of time.

It is nonvolatile.

It takes much more time to retrieve data

because of the electromechanical nature.

It is cheaper than primary storage.

It can take place on a variety of media.


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SECONDARY STORAGE

Magnetic tape

Sequential access

Magnetic disks

Hard drives

Direct access

Magnetic diskettes


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MAGNETIC TAPE

A secondary storage medium on a large openroll or in a smaller cartridge or cassette.

Made of a thin magnetizable coating on a

long, narrow strip of plastic film.

Developed in Germany, based on magnetic

wire recording.


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MAGNETIC TAPE


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SEQUENTIAL ACCESS

Data access in which the computer system

must run through data in sequence in order to

locate a particular piece.

Refers to reading or writing data records in

sequential order, that is, one record after the

other.

For example, to read record 10, you would

first need to read records 1 through 9.


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SEQUENTIAL ACCESS

Difference between sequential access torandom access


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MAGNETIC DISKS and HARD DRIVES

MAGNETIC DISKS

HARD DRIVES

A form of secondary storage on a

magnetized disk divided into tracks and

sectors that provide addresses for variouspieces of data;

A form of secondary storage that stores dataon platters divided into concentric tracks

and sectors, which can be read by a

read/write head that pivots across the

rotating disks.


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MAGNETIC DISKS and HARD DRIVES


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DIRECT ACCESS

Data access in which any piece of data

retrieved in a nonsequential manner by locating

it using datas address.

Method of transferring data from the

computers RAM to another part of the

computer without processing using the CPU.


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MAGNETIC DISKETTES

A form of easily portable secondary storage

on flexible Mylar disks.

Also called floppy disks.


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OPTICAL STORAGE DEVICES

A form of secondary storage in which a laser

reads the surface of a reflective plastic platter.

A term from engineering referring to thestorage of data on an optically readable

medium.


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OPTICAL STORAGE DEVICES

An electro-mechanical unit that can save and

retrieve (write and read) information on a

special disc medium using a laser light.

Data is recorded by making marks in a pattern

that can be read back with aid of light, usually

a beam of laser light precisely focused on a

spinning disc.


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COMPACT DISK, READ-ONLY

MEMORY (CD-ROM)

A form of secondary storage that can be only

read and not written on.

An adaption of the CD that is designed to

store computer data in the form of text and

graphics, as well as hi-fi (high fidelity) stereo

sound.


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COMPACT DISK, READ-ONLY

MEMORY (CD-ROM)


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DIGITAL VIDEO DISK (DVD)

An optical storage device used to store digital

video or computer data.

Commonly used as a medium for digitalrepresentation of movies and other multimedia

presentations that combine sound with

graphics.


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DIGITAL VIDEO DISK (DVD)


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FLUORESCENT MULTILAYER DISK

(FMD-ROM)

An optical storage device with much greater

storage capacity than DVDs.

Is a new data storage format currently being

developed by a company called

constellation 3D (C3D).


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FLUORESCENT MULTILAYER DISK

(FMD-ROM)

FMD is an optical format, similar in size and

appearance to regular CD-ROMs and

DVDs.

The advantage of FMD technology

promises over its rivals is that although a

CDR may hold 700MB of data, and a DVD-ROM 4.7, initial reports from C3D claim that

it may be possible to produce FMD discs

with up to 140 GB of data.


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MEMORY CARDS

Credit-card-size storage devices that can beinstalled in an adapter or slot in many personal

computers.

An electronic flash memory data storage

device used for storing digital information.

They are commonly used in many electronicdevices, including digital cameras, mobile

phones, laptop computers, MP3 players, and

video game consoles.


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MEMORY CARDS


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EXPANDABLE STORAGE DEVICES

Removable disk cartridges used as backup

storage for internal hard drives of PCs.


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ENTERPRICE STORAGE SYSTEMS

An independent, external system withintelligence that includes two or more storage

devices.

Is a centralized repository for businessinformation that provides common data

management and protection, as well as data

sharing functions, through connections to

numerous (and possibly dissimilar) computer

systems.


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REDUNDANT ARRAYS OF

INDEPENDENT DISKS (RAID)

An enterprise storage system that links

groups of standard hard drives to a

specialized microcontroller that coordinates

the drives so they appear as a single logicaldrive.

Is a way of storing the same data in different

places (thus, redundantly) on multiple hard

disks.


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Storage area network (SAN)

An enterprise storage system architecture for

building special, dedicated networks that

allow rapid and reliable access to storage

devices by multiple servers.


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Storage Area Network (SAN)


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Storage over IP

Technology that uses the internet protocol totransport stored data between devices within

a SAN

Sometimes called IP over SCSI oriSCSI(internet protocol)-(small computer

system interface)-(internet small computer

system interface)


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Storage over IP

Small Computer System Interface

SCUZZY

Is a set of ANSI standard electronic interfacesthat allow personal computers to communicate

with peripheral hardware such as disk drives,

tape drives, CD-ROM drives, printers, and

scanners faster and more flexibly than previousinterfaces.


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Storage over IP

Internet Small Computer System Interface

IP-based storage networking standard for linking

data storage facilities, developed by the internet

engineering task force.


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NETWORK-ATTACHED STORAGE

(NAS)

NAS device is a special-purpose server that

provides file storage to users who access the

device over a network; plug-and-play.

A hard disk storage that is set up with its own

network address rather than being attached to

the department computer that is servingapplications to a networks workstation users.


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END

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Comphar Midterm Lec1 (Memory Basic)

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