Page 359 - FUNDAMENTALS OF COMPUTER

NPP

NPP Memory 359

now this word and the corresponding block will Š`m|{H$ A~ CPU H$mo Yr_r J{V H$s _oZ _o_moar go S>mQ>m
be transferred from main memory to cache. n‹T>Zm hmoJm Ÿ& {H$gr Ho$qeJ {gñQ>_ _| Ho$e {_g H$s g§»`m
Since main memory is slow, it will take more
time. Thus the number of cache misses must be H$_ go H$_ hmoZm Mm{hE Ÿ&
as small as possible.
Hit Ratio: It may be defined as the ratio of {hQ> AZwnmV: `h Hw$b Ho$e {hQ>m| d Hw$b g§X^m] H$s
total number of hits to the total number of ref- g§»`m H$m AZwnmV hmoVm h¡Ÿ& Bgr go {H$gr Ho$qeJ {gñQ>_
erences made by CPU. The performance of a H$s JwUdÎmm Zmnr Om gH$Vr h¡Ÿ& BgH$m _mZ A{YH$ go
caching system is measured in terms of hit ra-
tio. It must be as high as possible. A{YH$ hmoZm Mm{hE Ÿ&
4.11 Comparison of memory 4.11 _o_moar H$s VwcZm

Secondary Memory Main memory Cache memory

Largest Intermediate size Smallest
Slowest moderate speed Fastest
lowest Cost per bit moderate Cost per bit Highest Cost per bit
goH§$S>ar _o_moar _oZ _o_moar Ho$e _o_moar
g~go ~‹S>r _Ü` AmH$ma g~go N>moQ>r
g~go Yr_r _Ü`_ J{V g~go VoO
g~go gñVr _Ü` H$s_V g~go _h§Jr

4.12 Types of Memory depending 4.12 EŠgog ‘moS> Ho$ AZwgma _o_moar Ho$ àH$ma
upon Access mode
Access refers to read or write. There are EŠgog go VmËn`© h¡ {H$ _o_moar H$mo n‹T>Zm `m Cg_|
three types of memory depending upon access: {bIZm& BgHo$ AmYma na VrZ àH$ma H$s _o_moar hmoVm h¡…