IT 104
133
FIGURE 4-l
134
IT I04
135
136
IT104
ITIfJ4
137
133
IT104
IT 104
139
!
140
IT 104
i‘
IT 104
141
I-
142
-r------
Disk
IT104
rr 104
143
144
IT 104
IBM PC/XT/AT
seagate
Hard Dtsk
Chsk capmty
(bytes)
Track capac.
Ity (bytes)
No of cylm
ders
Tracks per
Cyknder
Avg seek tme
IT
in4
3330
3340
3350
33%
&zOM 1 :sF
8,704
13~030
6366
19,069
3’ 744
820
404
696
555
1~500
1 g,,e
: -..
19
30 rns
12
25 ms
30
25 nls
.12
30 ms
12
19 nls
‘:
1Ei*
63ms
tO1ms
63~1s
806K
6&K
625K
1.198K
571M
3375
1M)M
6
40 ms
7 0 M 316M
3370
40M
Avg mtat~onal
delay
Data transter
rate (per sec‘JW
IBM-Type D!sk Drwe
35616
474*
10lms
10tms
63*
1 859K
1.659K
3~*
145
mr
146
I:
IT104
FIGURES-12
IT104
147
148
IT 104
IT
104
149
I
150
IT104
FIGURE 4-15
Watwe record organizahon
on disk,
Record
Number
IT 104
151
152
IT JO4
IT 104
153
Adding record
FIGURE 4-17
121 lo Ihe end
01 the indexed file cwses a
new entry in the index that
identities the record’s loca.
lion I” the file.
154
,ndex
l%mid
Number
,20
,
121
9
122
2
125
3
1M
s
137
6
1.1
I
143
0
N”llW~
*mount
126
1
DUB
IT 104
1.
2;
3.
4.
5.
6.
7.
6.
12.
13.
14.
15.
16.
17.
18.
156
IT 104
Access arm
Access time
Backup
CD ROM
Dala.base
Data rate
Directory
Disk cartridge
Field
IT104
File
FIxed disk
Floppy disk
Hard disk
indexed file
Indexed sequential
access method
(ISAM)
RAM disk
ReadWrile head
Record
Relative file
Removable disk
Root
Secondary srorage
Seclor
Sequence field
Sequential file
Subdwectory
Tape backup system
Track
157
1.
2.
3.
4.
5,
6
disk generalI? has the capacity far 1011 to over 100\1 in &
larger personal computers~
The
disk drive uses removable disks that are placed in a pro&tip,
sleeve when not in use.
T h i s list ma! ‘&
A list of files contained on a disk is known as a
displayed b? a DOS command or by user software.
is positioned on the surface of the disk by&
The
access arm to read or write data magneticall?..
A(n)
allow several related files to be accessed either sequential:
or directly.
provides a fixed disk drive that ma\ be mount+,:
. Alnl
in an empty expansion card slot in the computers
A(n)
Matching Ouestim
hlatch each term
a. root
b. data rate
c. R4.U disk
with the description @en belot\-,
d. ISA.\f
e. CD ROM
1. tape backup system
I. One way to speed up the use of software is to place some of :Lprogram in memor?. This method lets memory act like a disk drfr+
2. This is one way of creating a grandfather. father. son copy of tL.r
contents of a hard disk.
3. This device provides storage of large amounts of data. but the compu:+
cannot usually write data to the device.
4. This is the first level of a hierarchical subdirectory from which of’.,
directories branch.
5. A file access method that permits reading records either sequentia:..
or directly.
6. This term refers to the number of bytes per second that data are rea4
from a disk drive.
158
IT 104
IT 104
159