by Dinesh Thakur Category: Memory

The disk controller is circuitry on the computer's motherboard or on a plug-in circuit board that controls the operation of your hard disk drive, floppy disk drives, or both. When the computer wants to transfer data to or from the disk, it tells the disk controller. The controller in turn sends electronic commands to the disk drive making the disk spin and move its magnetic heads to the proper location on the disk. The controller then transfers the data between the computer and the disk drive. The computer's OPERATING SYSTEM and BIOS issue commands directly to the controller to BOOT the computer and to access files stored on the disks. 



 
by Dinesh Thakur Category: Memory

The cycle time of a computer is the time required to change the information in a set of registers. This is also sometimes called the state transition time. The register cycle time of a processor is sometimes referred to as the internal cycle time, clock time, or simply cycle time. Main memory cycle time is usually several times the internal cycle time. The internal cycle time may not be of constant value.



 
by Dinesh Thakur Category: Memory

Definition: Auxiliary memory (also referred to as secondary storage) is the non-volatile memory lowest-cost, highest-capacity, and slowest-access storage in a computer system. It is where programs and data kept for long-term storage or when not in immediate use.

Such memories tend to occur in two types-sequential access (data must access in a linear sequence) and direct access (data may access in any sequence). The most common sequential storage device is the hard disk drives, whereas direct-access devices include rotating drums, disks, CD-ROMs, and DVD-ROMs.It used as permanent storage of data in mainframes and supercomputers.



 
by Dinesh Thakur Category: Memory

Memory mapping is the translation between the logical address space and the physical memory. The objectives of memory mapping are (1) to translate from logical to physical address, (2) to aid in memory protection (q.v.), and (3) to enable better management of memory resources. Mapping is important to computer performance, both locally (how long it takes to execute an instruction) and globally (how long it takes to run a set of programs). In effect, each time a program presents a logical memory address and requests that the corresponding memory word be accessed, the mapping mechanism must translate that address into an appropriate physical memory location. The simpler this translation, the lower the implementation cost and the higher the performance of the individual memory reference.



 
by Dinesh Thakur Category: Memory

A typical hard disk is built right into your computer or is housed in a box nearby-and you never see the actual hard disk or take it out of its container. A cartridge hard disk, though, is removable. It works kind of like a giant floppy disk in that it slips into a slot in a special kind of removable hard drive case (actually, it's more like sliding a video tape into a VCR).

A typical cartridge hard disk holds 44 megabytes (there are also 88s), costs as little as $40, and is about as big as a cheese sandwich with no lettuce. The drive (the case) that you put the cartridge into costs from $450 to $1000.But once you have the hard drive, buying a new cartridge is the cheapest way to increase the amount of hard disk space you have.



 
by Dinesh Thakur Category: Memory

Definition: A disk cache (cache memory) is a temporary holding area in the hard disk or random access memory (RAM) where the computer stores information that used repeatedly. The computer can use it to speed up the process of storing and accessing the information much more quickly from the disk cache than if the information stored in the usual place (which might be on a disk or in a part of the computer's memory that takes longer to access). The term disk cache can also refer to a disk buffer and cache buffer.



 
by Dinesh Thakur Category: Memory

Definition: A buffer is Like a cache, that is a data area of computer memory (RAM) reserved for temporary storage. For instance, you've probably noticed that you can quickly type a bunch of commands on the keyboard, and then just sit back and watch your computer carry out the commands one after another. This is because the computer stores the keys you pressed in a buffer-after doing one command; it goes back to the buffer to get the next one in line.



 
by Dinesh Thakur Category: Memory

Associative memory: A type of computer memory from which items may be retrieved by matching some part of their content, rather than by specifying their address (hence also called associative storage or Content-addressable memory (CAM).) Associative memory is much slower than RAM, and is rarely encountered in mainstream computer designs.



 
by Dinesh Thakur Category: Memory

Associative Cache: A type of CACHE designed to solve the problem of cache CONTENTION that plagues the DIRECT MAPPED CACHE. In a fully associative cache, a data block from any memory address may be stored into any CACHE LINE, and the whole address is used as the cache TAG: hence, when looking for a match, all the tags must be compared simultaneously with any requested address, which demands expensive extra hardware. However, contention is avoided completely, as no block need ever be flushed unless the whole cache is full, and then the least recently used may be chosen.

 
by Dinesh Thakur Category: Memory

Hard Disk Access time is the total elapsed time between the initiation of a particular request for data and receipt of the first bit of that data.

Direct access devices (Hard Disk Drive) require varying times to position a disk head over a particular record. In the case of a moving-head disk drive, this involves positioning the comb (head assembly, as in Fig.) to the designated cylinder, plus rotation of the selected track to the desired record. Comb-movement times for a typical medium-sized disk drive are shown in Fig.



 
by Dinesh Thakur Category: Memory

In computing, an access method is a program or a hardware mechanism that moves data between the computer and an outlying device such as a hard disk (or other form of storage) or a display terminal.



 
by Dinesh Thakur Category: Memory

Storage Device is a device for recording (storing) information (data). Recording can be done using virtually any form of energy.storage device is a hardware device capable of storing information. There are two storage devices used in computers; a primary storage device such as computer RAM and a secondary storage device such as a computer hard disk drive.



 
by Dinesh Thakur Category: Memory

Printers are Output devices used to prepare permanent Output devices on paper. Printers can be divided into two main categories :

 
by Dinesh Thakur Category: Memory

ROM Definition: It is an example of nonvolatile memory.  ROM full form is Read Only Memory. It is a class of storage medium used in computers and other electronic devices. Read Only Memory (ROM), also known as firmware, is an integrated circuit programmed with specific data when it is manufactured. The instructions for starting the computer are housed on Read only memory chip.



 
by Dinesh Thakur Category: Memory

CISC (Complex Instruction Set Computer) : It was developed by Intel. CISC is a type of design for the computers. CISC based computer will have shorter programs which are made up of symbolic machine language.



 
by Dinesh Thakur Category: Memory

Random Access Memory (RAM) is the best known form of Computer Memory. The Read and write (R/W) memory of a computer is called RAM. The User can write information to it and read information from it.With Ram any location can be reached in a fixed ( and short) amount of time after specifying its address.



 
by Dinesh Thakur Category: Memory

Definition: Flash memory (Known as Flash Storage) is a type of non-volatile storage memory that can be written or programmed in units called “Sector” or a “Block.” Flash Memory is EEPROM (Electronically Erasable Programmable Read-Only Memory) means that it can retain its contents when the power supply removed, but whose contents can be quickly erased and rewritten at the byte level by applying a short pulse of higher voltage. This is called flash erasure, hence the name. Flash memory is currently both too expensive and too slow to serve as main memory.

 
by Dinesh Thakur Category: Memory

Until now you may have not seriously considered using a printer. After all, if you do not use your personal computer to play or to calculate your family budget you do not really need a hard copy of what is displayed on the screen.



 
by Dinesh Thakur Category: Memory

The devices which are used to input the data and the programs in the computer are known as "Input Devices". or  Input device can read data and convert them to a form that a computer can use. Output Device can produce the final product of machine processing into a form usable by humans. It provides man to machine communication. Some of the I/O devices are explained below:



 
by Dinesh Thakur Category: Memory

All Optical media (CD, DVD, Blu-Ray etc.) have pits and lands. These are microscopic and represent the binary information of the data stored on the disc. A land is reflective and reflects the laser into a sensor to register it as a I, but when the light hits a pit, it shatters and no reflection is received, thus a O is registered



 

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About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.