3 on numbers – Matrix Orbital PK202-24-USB User Manual
Page 36
8.3 On Numbers
Like all computerized devices, the display operates with commands and values in the form of binary
numbers. These binary numbers are arranged in 8 digit (i.e., 8 bit) groups called bytes. The decimal value
of a byte may have any value from 0 to 255.
Bytes are usually specified in either decimal or hexadecimal (base 16) form for convenience, since binary
numbers are confusing to deal with directly. Hexadecimal (hex) numbers are particularly convenient because
exactly two hexadecimal digits make up one byte, each hex digit representing 4 binary digits (4 bits) as shown
in the Table below.
Table 23: Hex Value Table
Binary Hex Decimal Binary Hex Decimal
0000
0
0
1000
8
8
0001
1
1
1001
9
9
0010
2
2
1010
A
10
0011
3
3
1011
B
11
0100
4
4
1100
C
12
0101
5
5
1101
D
13
0110
6
6
1110
E
14
0111
7
7
1111
F
15
Based on the table, the byte 01001011 can be represented in hex as 4B, which is usually written as any
of 4Bh, 4BH, 4B hex or 0x4B.
The numbers can be expressed in decimal form if preferred.
8.3.1 ASCII Characters
Since computers deal internally with numbers only, but externally with both letters and numbers, several
schemes were developed to ’map’ written characters to numeric values. One such scheme has become
universal; the American Standard Code for Information Interchange, or ASCII. ASCII tables are readily
available from a number of sources. A few examples will do here;
Table 24: Example of an ASCII Table
The letter
A
has a value of
65 decimal or
41 hex
The letter
a
has a value of
97 decimal or
61 hex
The number
0
has a value of
48 decimal or
30 hex
The number
9
has a value of
57 decimal or
39 hex
This gives rise to the possibility of confusion when parameters are being set on the display. For example,
the GPO ON and OFF commands use a number to indicate which GPO is being controlled. We’re told that
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PK202-24-USB
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