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(4) Vertical position data (b
The vertical position data specifies which of the 12 rows (vertical positions) shown in Fig. 20-10 the display
is to begin at. The vertical position data consists of four bits of the control data, with b
to the MSB and b
corresponding to the LSB, and it takes a value from 0H to DH. Value 0H corresponds
3
to row 0, and value DH to column 13.
A character position at the beginning of the screen is specified with an absolute row number (row from
0 to 11 in Fig. 20-10). The number of rows left blank between two rows is specified by the vertical position
data. In other words, the position of the next character is specified by the number (in hexadecimal) of
blank rows after the current row.
In Fig. 20-10, for example, the vertical position data of A and that of B are 6H and 1H, respectively. Similarly,
the vertical position data of D is 0H.
Remark The term number of rows used in the above description applies when the vertical size data is 00
(standard size). If the vertical size data is changed, the rows are counted based on the new vertical
size data. If the vertical size data is a double size, for example, one screen has only six rows.
Column
0
1
Row 0
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Row 7
Row 8
Row 9
Row 10
Row 11
Row 12
Row 13
260
to b
of the control data)
6
3
Fig. 20-10 Display Positions
2
3
4
5
6
7
B
D
8
9
10
11
12
13
A
C
PD17062
corresponding
6
Column
14
15
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