Page 360 - FUNDAMENTALS OF COMPUTER

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360 Fundamentals of Computers NPP

1. Random Access Memory 1. a|S>_ EŠgog _o_moar
2. Serial Access Memory 2. gr[a`b EŠgog _o_moar
3. Semi-random Access Memory 3. go_r-a|S>_ EŠgog _o_moar
1. Random Access Memory 1. a|S>_ EŠgog _o_moar
Any location within the memory can be {H$gr ^r _o_moar Ho$ a{OñQ>a H$mo {~Zm {H$gr H«$_ Ho$
accessed by placing its address. There is no n‹T>m Om gH$Vm h¡Ÿ& BgHo$ {bE _o_moar Ho$ ES´>og ~g na
specific order in which the memory locations
needs to be accessed. Both RAM and ROM are ES´>og S>mbH$a Amdí`H$ a{OñQ>a Ho$ AÝXa pñWV ~mBZar
random access memory. g§»`m H$mo n‹T>m Om gH$Vm h¡Ÿ& RAM VWm ROM XmoZm| hr
a|S>_ EŠgog _o_moar h¡Ÿ&
2. Serial Access Memory 2. gr[a`b EŠgog _o_moar
The information stored in this type of Bg àH$ma H$s _o_moar go EH$ {deof H«$_ _| hr OmZH$mar
memory can be accessed in a strict serial order H$m AmXmZ-àXmZ {H$`m Om gH$Vm h¡Ÿ& Bg_| {H$gr àH$ma
only. There is no address asigned to the locations. H$m ES´>og Zht hmoVm h¡Ÿ& Bg{bE Bgo non-addressable
Thus, it is called non-addressable memory. For
example, a magnetic tape is an example of serial memory H$hVo h¢ O¡go, Mwå~H$s` Q>on EH$ nyU©V… gr[a`b
access memory. In magnetic tape, a head is used EŠgog _o_moar h¡& Bg_| EH$ hoS> hmoVm h¡, Omo n‹T>Zo d
to read or write a bit in serial fashion. This can {bIZo H$m H$m`© H$aVm h¡& Bgo {MÌ _| Bg àH$ma Xem©`m
be shown in the following diagram: Om gH$Vm h¡…

Read write head

1 0 1 0 0 0 1

track

Magnetic tape Movement of tape
3. Semi-random Access Memory 3. AY©-aoÝS>_ EŠgog _o_moar
In this type of memory, both serial and Bg àH$ma H$s _o_moar _| XmoZm| àH$ma Ho$ EŠgog hmoVo
random access are there. This cannot be a fully h¢ Ÿ& Zm Vmo `h nyU©V… gr[a`b EŠgog h¡ Am¡a Zm hr `h
serial or full random access memory. For
example, Hard disk and floppy disks are semi nyU©V… aoÝS>_ hmoVr h¡ Ÿ& O¡go, hmS>©-{S>ñH$ d âbm°nr-
random access memory. When a head rests an {S>ñH$ & O~ hoS> {H$gr Q´>oH$ na hmoVm h¡ Vmo `h {H$gr ^r
a particular track, it can jump randomly to any Xygao Q´>oH$ na Om gH$Vm h¡ & `h EH$ a|S>_ EŠgog hþAmŸ&
other track, since the head can move inward bo{H$Z O~ hoS> EH$ Q´>oH$ na hmoVm h¡ Vmo {H$gr goŠQ>a H$mo
and outward, when it want to access a particular
sector on a track, it will wait for that sector. {g\©$ gr[a`b EŠgog H$a gH$Vm h¡Ÿ& Bg goŠQ>a Ho$ {bE
Thus, sector reading or writing is concerned hoS> BÝVOma H$aVm h¡Ÿ& Bg àH$ma goŠQ>a arqS>J `m amBqQ>J