Home Computer How Computer Hardware Memory(RAM, ROM Drive) Works

How Computer Hardware Memory(RAM, ROM Drive) Works

by Yolando B. Adams



The microprocessor is the brain of any laptop. It controls all activities on the computer. Basically, it performs 2 kinds of operations – mathematics & logical operation (internally), read & write (externally). Read /write operations are completed on 2 varieties of gadgets – I/O and reminiscence gadgets. It uses the “cope with a bus” to choose any “vicinity” on those gadgets, sends a study/writes signal over the “manage bus” after which the records over the “information bus”.


The CPU stores all facts within the laptop’s memory.

Computer has two memory kinds – RAM & ROMComputer

RAM (Random Access Memory):

This volatile kind is a study & write memory device. This loses its contents while electricity is close off.

The kinds of RAM are

· DRAM (Dynamic ram) – is similar to a capacitor, because it has a tendency to lose its contents and consequently requires to be refreshed. This is the Computer RAM.



· SRAM (Static ram) – Is faster than Dram and would not require being refreshed. This is expensive and hence handiest a confined quantity is used as CACHE reminiscence in the computer.

ROM (Read only memory):

ROM may be programmed using a programmer and then it acts as a “examine only” device. This tool is used because the textbook for the CPU in the computer and is referred to as ROM BIOS. It shops all of the simple information of programming the gadgets gift inside the device as well as the POST (Power On Self Test) collection. AMI BIOS and AWARD BIOS are the maximum common ROM BIOS.

The varieties of ROM are

· PROM (Programmable Read Only Memory)

· EPROM (Erasable & Programmable Read Only Memory)


· EEPROM (Electrically EPROM)

· EEPROM (Electrically Alterable ROM)


Apart from passive reminiscence devices, there are sure controllers in the device, which assist the CPU in acting diverse operations. These are called I/O devices. These devices encompass Interrupt controller, Timer, Ports, DMA Controller, Floppy Drive Controller, CRT Controller etc.


These are the manner thru which verbal exchange between various gadgets of the pc takes place and the kids are as noted under.

ISA (Industry Standard Architecture):

ISA bus consists of a 24-bit address bus and the sixteen-bit facts bus. ISA can help 8MHZ clock pace.

MCA BUS (Micro Channel Architecture):

MCA bus is to be had either in sixteen bit or 32-bit versions. It was developed in a brand new line of computer systems known as the PS/2 (private system 2). The clock velocity is barely faster (10MHZ rather than 8MHZ).


EISA has a 32-bit Address and Data bus and 10MHZ CLK speed.


It is a 32-bit bus which becomes located neighborhood to the CPU and as a result its name. Therefore it may guide high bus speeds (that of the CPU).

PCI BUS:mermory

PCI has many benefits over different bus kinds. First of all, it helps 64 bit and 32-bit records paths. So it is able to be used both for 486 and Pentium based totally systems. PCI can run up to 33MHZ velocity and has the benefit of being removed from the CPU. INTEL evolved this bus.

PCMCIA: (PC Memory Card International Association):

The PCMCIA changed into first designed for increasing the reminiscence in small, handled computers. PCMCIA bus width is simplest sixteen bits, but a 32-bit model is on its way. There are 3 sorts of playing cards particularly

· Type 1 (3.Three m thick)- used for the memory card.

· Type 2 (5 mm thick)- used for modem and LAN adapter.

· Type 3 (10.5 mm0 thick) – used for most common packages like PC hard disk Cards.


These are playing cards plugged on to the primary board, the mom board (The one that homes the CPU & RAM/ROM Bios). Each plays specific functions of interfacing the Motherboard to a peripheral device like the mouse, Monitor and so forth. Some Add-ons are discussed beneath.


These interface the motherboard with the display and there are several forms of cards. The variations are in resolution, no. Of hues supported and velocity.

CGA (Color Graphics Adapter)

640 X two hundred pixels

MDA (Mono Display Adapter):

eighty characters extensive 25 lines lengthy

EGA (Enhanced Graphics Adapter):

640 X 350 mode

VGA (Video Graphics Adapter):

Advanced variations of SVGA/TVGA which start from a resolution of 640 X 480 pixel

AGP (Accelerated Graphics Port):

Introduced within the Celeron/P II primarily based structures, this caters to the annoying multimedia applications with its excessive performance.


Supports the subsequent functions.


Communication external to the computer is executed serially (bit after bit) thru this port. It is used to attach conversation gadgets like the mouse, modem etc.


eight Bit statistics switch takes area between the pc and an outside device. It is normally used to attach a printer.


It is used to attach a joystick to playing video games.

IDE (Integrated/Intelligent Drive Electronics) Interface: This interface is used to talk with IDE Hard disks.


The FDC can guide up to 2 floppy disk drives. The FDC is attached to the device bus and to the DMA controller. It performs statistics switch in DMA mode.


This is the cardboard that provides audio results to the laptop by way of offering the interface with microphone and speaker. This is used in Multimedia Computers.



1.44 MB & 1.2 MB are two sorts of popular Floppy Drives.


ST 506 & ESDI are antique kinds. IDE hard disks are popular because their price to overall performance ratio is superb. For very excessive performance, SCSI (Small Computer Systems Interface) is the precise option, if the charge isn’t a criterion.


CDROM pressure is utilized in a multimedia gadget as it could aid all sorts of CD ROMs – be it records CD, Audio CD, Video CD. It has a terrific advantage of storing about 650 MB of information in a single CD.


Keyboard interprets the keystrokes into letters or numbers. These letters are interpreted and the laptop CPU depending executes commands on what changed into sent. Variations in terms of XT/AT, no. Of keys, kind of keys used may be determined.


To interact with the pics (ICONS), a special pointer device became added into the computer global. This tool is referred to as mouse and is attached to the serial port.

The mouse carries a spherical ball that makes touch with rollers-one for X-axis (the horizontal) and one for Y-axis (the vertical). Moving the mouse causes the ball to roll, and the ball, which is in contact with the two rollers, reasons them to turn. This is used for shifting clicking the mouse buttons makes a pointer head at the display screen and selection.


In addition to keyboards and pointing gadgets, there is any other very commonplace approach to getting information into the laptop. A Scanner is used to scan a picture (say from a photo) and editing can be accomplished the use of an appropriate software.


The display gets video indicators from the computer video adapter card and presentations the video information as pixels (picture elements) at the display. A type of video display units starting from CGA mono to SVGA shade is to be had for users to choose from (though the former is absolutely obsolete).


This is where we define the gadget configuration. This is done only while the system is assembled and configured for the first time or while it is upgraded. (One might also input the SETUP by means of urgent “Del” key because the device is powered up). Different BIOS’ guide distinct alternatives but the maximum critical ones, which might be located on all systems, are listed below.

DATE & TIME: It displays an appropriate Date & Time. It must be set whilst gadget is first hooked up.


To outline the Floppy drives related (1.2MB or 1.44MB).

HARD DISK TYPE: To pick the Hard disk type (Primary or secondary)

DISPLAY TYPE: Its choose the forms of video adapter used for the system screen.


This class hastens the Memory get entry to. (Default fee: Enable) and defines presence or absence of cache reminiscence.

QUICK POWER OF SELF TEST: It accelerates the Power On Self Test after you electricity up the pc.

PASSWORD SETTING: This lets you to set the System password.

POWER MANAGEMENT: This category allows you to pick the kind (or diploma) of energy saving.


There are many parameters, which want to be described in the CMOS setup, and one won’t want to accomplish that manually. This choice loads sure default values, saved in the BIOS ROM, that has been described by means of the producer for foremost device overall performance.


To allow/disable sure onboard functions like Floppy Disk Control etc (This applies best to integrated Motherboards wherein the ADD-ON features are included on the Motherboard itself).

PNP FEATURES: This category is used to configure the PCI Bus slots.

IDE AUTO DETECTION: This lets in you to discover the IDE Hard drives routinely.


This permits you to keep the new setting fee within the CMOS memory and maintain with the booting technique.


This POST firmware is saved in ROM on the motherboard. This POST is a chain of a simple program to check and catch faults in different additives and circuits. It exams the microprocessor, interrupt controller, PPI, DMA controller, ROM, RAM, peripheral controllers and so on.


In case of mistakes detection at some stage in a POST, symptoms like mistakes beeps/errors messages facilitate troubleshoot issues.


With the help of speaker blunders beeps, we can troubleshoot faults. Each fault reasons the speaker to emit exclusive patterns of beeps.


When a device is powered on, the error message may be displayed on the display (Floppy disk fail), if the Video Adapter is purposeful.


The superior diagnostic upload on card captures info of POST series and shows a hex code which can be used for in-depth & accurate diagnosis of a POST trouble.


A laptop CD-ROM drive makes use of small, interchangeable, plastic-encased discs from which facts is retrieved using a laser beam, similar to song compact disc. And like a song CD, a computer CD-ROM shops giant amounts of information. This is performed by using the usage of mild to report records in a form it really is extra tightly packed than the distinctly clumsy magnetic study/write heads a traditional drive must manage.

The drive is managed by way of a software for your PC that sends commands to controller circuitry it’s both a part of the computer’s motherboard or on a separate board hooked up to an expansion slot.

How did a CD_ROM drive work?
· A motor continuously varies the rate at which CD-ROM disc spins so that regardless of wherein a factor, referred to as DETECTOR, is positioned with regards to the radius of the disc, the part of the disc straight away above the detector is always at the equal pace.

· The laser tasks a focused beam of light this is in addition targeted by means of a focusing coil.

· The laser beam penetrates a defensive layer of plastic and strikes a reflective layer that looks like aluminum foil on the lowest of a disc.

· The surface of the reflective layer alternates between lands and pits. Lands are flat surface areas; pits are tiny depression inside the reflective layer. These surface are a document of the 1s and 0s used to shop records.

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