02:

2

: - Megatron 747 :

2

2

PMC......

2

, , RISC/CISC, , ,...Speed: 100 500 1000 MIPS , , , (ROM),... : 10-6 10-9 sec. 1 s 1 ns

2

:- : (, ) , CD-RO - : , -

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: : , ,, , (), (), ,

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T : 1 15 : 100 2000 :1 (CDs) (./.) 2 () 30 : 512B 50K : 360 KB () 120 GB

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.? X

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= + + +

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( )3 or 5xx1N-

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SEEKTIME (i j)S = N(N-1) N Ni=1j=1jiT S: 5 20

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2

R = 1/2

R = 4.167 (7200 /)

2

,

2

: t t: 60 100 MB/ : t

2

I/O , T : 0

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() ?

2

I/O( ) = + t

- - -

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() :1 KB Block I/O: 10 . I/O: 0.5 .

2

, ! () + t

2

2

:

2

: 12. - .m

2

3.5 3600 /1 16 MB (16 X 220)128 : = 25 . = 5 .Megatron 747 ()

2

= 1 KB = 1 10% = 16 MB = (220)16 = 224 = 128 = 27/. = 224/27 = 217 = 128 KB/ . = 128 KB / 1 KB = 128

2

3600 / 60 / 1 . = 16.66 ms :... : (16.66)(0.9) = 15 . : (16.66)(0.1) = 1.66 . 1 = 15/128 = 0.117 . .1 +. = 16.66/128 = 0.13.. = 1/0.117 = 8.53 / = 8.53*1KB*1000/*1MB/1024KB = 8.33MB/ ( 128KB 16.66 ) = 128/16.66 = 7.68 KB/ = 7.5MB/

2

T1 = T1 = + +

2

, 4 KB T4 = 25 + (16.66/2) + (.117) x 1 + (.130) X 3 = 33.83 [ T1 = 33.45 ms]...12341

2

TT = ( )

TT = 25 + (0.130/2) + 16.66* = 41.73 ms

* ;

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Megatron 747 ( 11.3)24 = 16 , 3.5 1 214 = 16384 /27 = 128 ( ) /212 = 4096 /237 = 128GB 219 = 512KB 1 128 , ~ 420000 / . ~ 990000 / . 96 ( .) 160 ( .), 530000 742000 / 7200 /

2

Megatron 747 ( 11.5), 1 1 1000 ( ). 1+16.383 = 17.383 = 60/7200 = 0.00833 . 16384- 36*3/128+324*4/128 = 10.97 16384- :.: 10.97/360*8.33 = 0.25 ( .): 17.38+8.33+0.25 = 25.96 : 1+ 5.641+4.17+0.25 = 10.88 (5641 - 2 )

2

(,) , ( ) ( )

2

: B1, B2,... B1 B2 B3

2

(1) B1 (2) (3) B2 (4) ...P = 1 R = 1 n = - = n(P+R)

2

:

:

2

P R ?P = 1 R = 1 n = - 2 = n(P+R) 1 = n(P+R)

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I/O , ...

2

10-910-610-310-0103 ()101510131011109107105103online-

offline () Gray & Reuter

2

10-910-610-310-0103 ()10410210010-210-4online-offline/MB Gray & Reuter

2

( 11.4): : I/O - I/O ?

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( 11.6) ?,

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, A B

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