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MEMORY
UNIT-3
Mohammad Asif IqbalAssistant Professor, Deptt of ECE,JETGI, Barabanki
BRAIN vs. MEMORY
WHAT WE WILL LEARN IN THIS LECTURE
Memory technologiesHierarchal organization Principle of locality Analysis of hierarchy Simple case organizations
TYPICAL SPECIFICATIONS OF COMPUTERS TODAY
MEMORY TECHNOLOGIES
SEMICONDUCTORRegisterSRAMDRAMFLASH
MAGNETICFDDHDD
OPTICALCDDVD
Random access
Random + sequentional
HIERARCHAL STRUCTURE
SPEED CPU
SIZE COST/ BIT
FastestMemory
Slowest
HighestFastest
Memory
Memory
Biggest Lowest
DATA TRANSFER BETWEEN LEVELS
PRINCIPLE OF LOCALITY
Temporal localityReferences repeated in timeThe concept that a resource that is referenced at one point in time will be referenced again sometime in the near future.
Spatial locality Reference repeated in spaceSpecial case: sequential localityThe concept that likelihood of referencing a resource is higher if a resource near it was just referenced.
MEMORY HIERARCHY ANALYSIS
CACHE ACCESS EXAMPLE.
Before the reference to Xn After the reference to Xn
X4 X4
X1 X1
Xn-2 Xn-2
Xn-1 Xn-1
X2 X2
Xn
X3 X3
DIRECT MAPPED CACHE
CACHE ACCESS MECHANISM
CACHE WITH 4 WORD BLOCKS
QUESTIONS
MM SIZE CACHE SIZE
BLOCK SIZE
TAG BITS TAG DIRECTORY
128 KB 16KB 256 B ------- -------
32 GB 32KB 1KB ------- -------
------- 512 KB 1 KB 7 -------
MORE FLEXIBLE BLOCK ARRANGEMENT
FULLY ASSOCIATIVE CACHE
Question:-MM:- 32 GBBLOCK:- 32 KBTAG= ?Propagation Delay Of Comparator=10 K nsPD of OR Gate= 10 nsHL=?
SET ASSOCIATIVE CACHE
MM SIZE CACHE SIZE BLOCK SIZE TAG BITS TAG DIRESTORY
SET ASSOCIATIVE
128 KB 16KB 256B ----- ----- 2-WAY
32GB 32KB 1KB ----- ----- 4-WAY
----- 512KB 1KB 7 ------ 8-WAY
16 17 18 19
20 21 22 23
24 25 26 27
28 29 30 31
32 33 34 35
36 37 38 39
40 41 42 43
44 45 46 47
48 49 50 51
52 53 54 55
56 57 58 59
60 61 62 63
52 53 54 55
40 41 42 43
12 13 14 15
0 1 2 3
4 5 6 7
8 9 10 11
12 13 14 15
01111000
01 00 11
01 11 11
11 01 01
10 10 11
MORE EXAMPLE OF DIRECT MAPPING
TAG LINE BO
MORE EXAMPLE OF SET ASSOCIATIVE MAPPING
0 1 2 3
4 5 6 7
8 9 10 11
12 13 14 15
16 17 18 19
20 21 22 23
24 25 26 27
28 29 30 31
32 33 34 35
36 37 38 39
40 41 42 43
44 45 46 47
48 49 50 51
52 53 54 55
56 57 58 59
60 61 62 63
01234567
0,41,52,63,7
TAG SET BO
MORE EXAMPLE OF FULLY ASSOCIATIVE MAPPING
0 1 2 3
4 5 6 7
8 9 10 11
12 13 14 15
16 17 18 19
20 21 22 23
24 25 26 27
28 29 30 31
32 33 34 35
36 37 38 39
40 41 42 43
44 45 46 47
48 49 50 51
52 53 54 55
56 57 58 59
60 61 62 63
TAG BO
THANK YOU!
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