Page 335 - FUNDAMENTALS OF COMPUTER

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NPP Memory 335

performed, the contents of cell may be {dZmer (Destructive Read out) H$hVo h¢ & O¡go
erased. This type of cell is called destructive DRAM H$s gob& Ÿbo{H$Z O~ n‹T>Zo Ho$ níMmV² gob
read-out cell. For example, dynamic RAM
cells. On the other hand, if the contents are H$s OmZH$mar ~Zr ahVr h¡, Vmo Bgo A{dZmer n‹T>Zm
not erased after a read operation, this is (Non-destructive Readout) H$hVo h¢Ÿ& O¡go
called a non-destructive read-out. For SRAM `m ROM H$s gob Ÿd gmar Mwå~H$s` _o_moar
example, static RAM or ROM cells. H$s gob ^r A{dZmer n‹T>Zo `mo½` hmoVr h¡Ÿ&
5. Read Only Cell or Read- Write Cell: If 5. arS> AmoZbr `m arS>-amBQ> gob: `{X gob _| go
only read operation can be performed, the {g\©$ n‹T>m Om gH$Vm h¡ Vmo Bgo arS> AmoZbr gob
cell is called read-only cell. For example, a H$hVo h¢Ÿ& O¡go, ROM H$s gobŸ& O~ n‹T>Zm d
cell in ROM is a read-only cell. If both read
and write operation can be performed, the {bIZm XmoZm| gå^d hmo Vmo Bgo arS>-amBQ> gob H$hVo
cell is called read-write cell. For example, h¢Ÿ& O¡go, RAM H$s gobŸ&
a cell in RAM.
Representation of a Memory Cell _o_moar gob H$m à{V{Z{YËd
The memory cell is a fundamental memory `h EH$ _yb^yV _o_moar VËd h¡ Š`m|{H$ Bg_| EH$ hr
element because it is used to store a bit. It may be {~Q> g§J«hrV hmoVr h¡& Bgo h_ ~mBZar gob H$hVo h¢ Š`m|{H$
called as binary cell because it has only two states
0 and 1. The cell can be represented as below: 0 `m 1 Xmo hr AdñWmE± Bg_| hmo gH$Vr h¢Ÿ& Bgo
{MÌmZwgma Xem©`m Om gH$Vm h¡:

D
Write

Memory
Cell

read

Q
Here, D is the input bit. It will be stored in `hm± na D EH$ BZnwQ> {~Q> h¡ d Q gob go {b`m
the cell only when write = 1. The information OmZo dmbm AmCQ>nwQ> h¡Ÿ& BZnwQ> D gob _| V^r OmEJm
stored in the cell can be obtained at output Q O~ write = 1 hmoŸ& gob _| g§J«{hV OmZH$mar Q na V^r
only when control line read = 1.
n‹T>r OmEJr O~ read = 1 h¡Ÿ&
Thus, Read and Write are Control Signals. AV…, Read d Write H§$Q´>mob {g½Zb h¡& D BZnwQ>
D is input signal and Q is output signal. {g½Zb VWm Q AmD$Q>nwQ> {g½Zb h¡&
4.2 Memory 4.2 _o_moar
Memory is part of the computer used to ‘o‘moar H$åß`yQ>a H$m dh {hñgm hmoVm h¡, Omo àmoJ«m_
store programs and data. There are two types d S>mQ>m g§J«hU Ho$ H$m_ _| AmVm h¡Ÿ& _w»`V: Xmo àH$ma
of memory:
H$s _o_moar hmoVr h¢ …