Unformatted text preview: it can be easily divided into two 4bit groups. Each of
these 4bit groups can be represented by 1 hexadecimal digit (refer to Chapter 3). Thus,
hexadecimal number system is used as shortcut notation for memory dump by computers
that use EBCDIC for internal representation of characters. This results in a onetofour
reduction in the volume of memory dump. Figure 4.3 shows the alphabetic and numerical
characters in EBCDIC along with their hexadecimal equivalent.
Developed by IBM, EBCDIC code is used in most IBM models and in many other
computers.
Character
EBCDIC Code
Hexadecimal Equivalent
A
B
C
D
E
F Zone
1100
1100
1100
1100
1100
1100 Digit
0001
0010
0011
0100
0101
0110 Cl
C2
C3
C4
C5
C6 G
H
I 1100
1100
1100 0111
1000
1001 C7
C8
C9 J
K
L
M
N
0
P
Q
R 1101
1101
1101
1101
1101
1101
1101
1101
1101 0001
0010
0011
0100
0101
0110
0111
1000
1001 Dl
D2
D3
D4
D5
D6
D7
D8
D9 S
T
U
V
w
X
Y
z 1110
1110
1110
1110
1110
1110
1110
1110 0010
0011
0100
0101
0110
0111
1000
1001 E2
E3
E4
E5
E6
E7
E8
E9 . 0
mi
0000
F0
1
mi
0001
Fl
2
mi
0010
F2
3
mi
0011
F3
4
nil
0100
F4
5
mi
0101
F5
6
mi
0110
F6
7
nil
0111
F7
8
nil
1000
F8
9
mi
1001
F9
Figure 4.3. Alphabetic and numeric characters in EBCDIC along with their Hexadecimal
eauivalent.
Zoned and Packed Decimal Numbers
From Figure 4.3 it can be observed that in the EBCDIC code, the digit values are the
same as the numeric characters  0 through 9 (0000  1001). But numeric values need
some special consideration because we must have a way of indicating whether the
number is positive, negative, or unsigned (implies positive). Thus, when a numeric value
is represented in EBCDIC, a sign indicator is used in the zone position of the rightmost
digit. A sign indicator of hexadecimal C is a plus sign, hexadecimal D is a minus sign,
and hexadecimal F means the number is unsigned. Figure 4.4 illustrates the representation of numeric values in EBCDIC. Note that the only zone affected by the sign
is the* zone of the rightmost digit. All other zones remain as F, the zone value for
numeric characters in...
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This document was uploaded on 04/07/2014.
 Spring '14

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