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20.4.1 ID Field
The ID field indicates the type of data in the data field.
The data field can hold the following three types of data.
(1) Character pattern select data
(2) Carriage return data
(3) Control data select data
ID field
b
7
0
0
1
1
20.4.2 Character Pattern Select Data
The character pattern is the data of an image displayed on a screen such as a TV screen. It is allocated
in the CROM area (at 0800H to 0F7FH) of program memory. The character pattern select data becomes part
(b
to b
) of a CROM address. In other words, the 6 bits of data in the data field indicate b
9
4
address.
CROM consists of BANK0 and BANK1. Note that even if the 6-bit VRAM data is the same, the CROM address
varies according to the value of the CROMBNK (b
the CROM address is 080 H (10000000
selects 080 H or 0C0 H. Table 20-4 lists the CROM addresses that the VRAM character pattern select data
actually points to.
Fig. 20-2 VRAM Data Configuration
Even address
b
b
b
b
7
6
5
4
(b
)
(b
)
(b
)
(b
)
3
2
1
0
ID field
Table 20-3 ID Field
Type of data in the data field
b
6
0
Character pattern select data
1
Carriage return (return address) to BANK1 (from BANK1 to
BANK1, and from BANK2 to BANK1)
0
Control data
1
Carriage return (return address) to BANK2 (from BANK2 to
BANK2)
at 30H). If the data field contains a value of 0 (000000B),
0
B) or 0C0 H (11000000
Odd address
b
b
b
b
3
2
1
0
(b
)
(b
)
(b
)
(b
)
3
2
1
0
Data field
B). Specifying the BANK of CROM
PD17062
to b
of the CROM
9
4
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