Page 22 - FUNDAMENTALS OF COMPUTER

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22 Fundamentals of Computers NPP

examples of IO devices are floppy disk, mo- âbm°nr {S>ñH$ d _moS>o_ Am{XŸ& AV: Bg àH$ma H$s {S>dmBgog
dem etc. H$mo BZnwQ>-AmCQ>nwQ> (IO) {S>dmBgog H$hm OmVm h¡Ÿ&

3. MEMORY 3. _o_moar
This block of computer works as a stor- H$å߶yQ>a H$m ¶h ãbm°H$ BÝ’$m°‘}eZ Ho$ {bE ñQ>moaoO
age for information. The memory can be Ho$ ê$n ‘| H$m¶© H$aVm h¡& H$åß`yQ>a H$s _o_moar Xmo àH$ma H$s
categorised as primary and secondary memory.
But the memory shown in the block diagram is hmoVr h¡ ; àm`_ar VWm goH§$S>ar _o_moar bo{H$Z Omo _o_moar
primary memory. It is also called main memory ãbm°H$ S>m`J«m_ _| Xem©B© OmVr h¡ dh àm`_ar _o_moar hmoVr
of computer because it is the only memory
which directly communicates with CPU. All h¡ Š`m|{H$ `hr CPU go grYo OmZH$mar bo `m Xo gH$Vr h¡Ÿ&
user programs and some monitor programs Cn`moJH$Vm© Ho$ gmao àmoJ«m_ VWm Hw$N> _m°ZrQ>a àmoJ«m_ nhbo
first go into main memory and then executed Bg_| AmVo h¢ V^r CPU Ûmam EpŠOŠ`yQ> (g§nÝZ) hmoVo
by CPU. The secondary memory is a perma-
nent storage memory. Therefore it is kept in the h¢& goH§$S>ar _o_moar EH$ ñWm`r ñQ>moaoO _o_moar h¡Ÿ& AV: Bgo
category of Input-output devices. BZwnQ>-AmCQ>nwQ> {S>dmBgog H$s loUr _| aIm OmVm h¡Ÿ&
There are two types of Primary memory: àm`_ar _o_moar Xmo àH$ma H$s hmoVr h¡…
1. RAM 2. ROM 1. RAM 2. ROM
RAM: (Random Access Memory) ao_… (aoÝS>_ EoŠgog _o_moar)
This is a main memory in which user pro- ¶h ‘w»¶ ‘o‘moar h¡ {Og‘| Cn`moJH$Îmm© Ho$ àmoJ«m_
grams reside just prior to their execution. There- {H«$`m§{dV hmoZo go R>rH$ nyd© ao_ _| hmoVo h¢Ÿ& Bgr{bE Bgo
fore it is called user memory. Both reading and Cn`moH$Vm© _o_moar (`yOa _o_moar) ^r H$hVo h¢Ÿ& Bg _o_moar
writing operations can be performed over RAM. _| {bIZo d n‹T>Zo XmoZm| H$s {H«$`mE± hmoVr h¡Ÿ& Bgr{bE Bgo
Therefore it is also called Read-write (R/W) R/W (Read-write) _o_moar ^r H$hVo h¢Ÿ& O~ {dÚwV ~§X
memory. When electrical power goes off the H$a Xr OmVr h¡ Vmo BgHo$ A§Xa H$s OmZH$mar Zï> hmo OmVr
contents in this memory are lost, therefore it is
called Volatile memory. The size of RAM h¡Ÿ& Bgr{bE Bgo dmînerb (Volatile) _o_moar ^r H$hVo
present in a system decides the overall work- h¢Ÿ& {H$gr H$åß`yQ>a _| ao_ H$s _mÌm go CgHo$ àmoJ«m_
ing speed of the computer. There are two types {H«$`mÝd`Z H$s J{V V` hmoVr h¡Ÿ& Xmo àH$ma H$s ao_ Cn`moJ
of RAM; Static RAM and Dynamic RAM. The _| bmB© OmVr h¡; ñQ>o{Q>H$ d S>m`Zm{_H$Ÿ& ñQ>o{Q>H$ ao_ VoO
Static RAM is faster but very expensive. The hmoVr h¡ naÝVw _h§Jr hmoVr h¡Ÿ& S>m`Zm{_H$ ao_ Yr_r naÝVw
Dynamic RAM is slower but very cheap. There- ~hþV gñVr hmoVr h¡Ÿ& Bgr{bE S>m`Zm{_H$ ao_ H$m AË`{YH$
fore Dynamic RAM is used extensively. Cn`moJ {H$`m OmVm h¡Ÿ&
ROM (Read Only Memory) ROM (arS> AmoZbr _o_moar)
Since only read operation can be performed O~ amo_ H$s {Mn H$mo H$åß`yQ>a _| bJm {X`m OmVm
it is called Read Only Memory. Programs in h¡ Vmo {g\©$ arS> (n‹T>Zm) H$s {H«$`m hmo gH$Vr h¡Ÿ& AWm©V²
ROM cannot be modified.This memory con- CPU BgHo$ A§Xa Ho$ àmoJ«m_ H$mo {g\©$ n‹T> gH$Vm h¡Ÿ&
tains certain monitor and control programs BgHo$ àmoJ«m_ _| H$moB© ^r n[adV©Z Zht {H$`m Om gH$Vm
which are necessary for the overall operation h¡ Am¡a Zm hr Cn`moJH$Vm© H$moB© àmoJ«m_ Bg_| {bI gH$Vm
of the computer. This memory is permanent or h¡Ÿ& Bg_| Hw$N> Q>oñQ> àmoJ«m_ VWm _m°{ZQ>a àmoJ«m_ hmoVo h¢&