TABLE 17. Auto Attribute Mode

ATTRIBUTE Byte

X

0

0

X

ATT[3:0]

When bits 6–5 are 0, the 4-bit attribute code will be automatically applied to all the character codes transmitted after this attribute

byte, as in the LM1237 and LM1247. This mode is useful for sending character codes that use the same attribute. No further

attribute codes can follow without stopping and restarting a new transmission. The Page RAM address is automatically

incremented starting with the initial LSB and MSB address in the beginning of the sequence.

TWO BYTE COMMUNICATION MODE

The Two Byte Communication mode allows different attribute and character codes to be sent within one transmission without

stopping. The attribute byte is shown in Table 18, and the sequence of transmitted bytes is shown in Table 19. Either another

attribute & character code pair or a STOP must follow after each character code. The Page RAM address is automatically

incremented just as in the Auto Attribute mode above.

TABLE 18. Two Byte Communication Mode

ATTRIBUTE Byte

X

0

1

X

ATT[3:0]

TABLE 19. Sequence of Transmitted Bytes

HALF RANDOM ADDRESS MODE

The Half Random Address mode allows different attribute and character codes to be sent within one transmission in the same

way as the Two Byte Communication mode. The advantage of Half Random Addressing over the Two Byte mode is that the Page

RAM addresses do not have to be written to in a sequential order. However, the Page RAM addresses cannot be entirely random,

as they must be within one half of the Page RAM. A new transmission must be restarted to switch to another half of the Page

RAM. The Page RAM address is not automatically incremented in this mode. This mode is very useful for modifying character

codes and attributes in the first 256 locations of the Page RAM. The attribute byte is shown in Table 20, and the sequence of

transmitted bytes is shown in Table 21. Either another LSB address & attribute & character code or a STOP must follow after each

character code.

TABLE 20. Half Random Address Mode

ATTRIBUTE Byte

X

1

0

X

ATT[3:0]

TABLE 21. Sequence of Transmitted Bytes

FULL RANDOM ADDRESS MODE

The Full Random Address mode is very similar to the Half Random Address mode. However, the advantage is that the Page RAM

addresses can now be entirely random. There is no longer a restriction to only one half of the Page RAM. The Page RAM address

is not automatically incremented in this mode. This is very useful for modifying character codes and attributes anywhere in the

Page RAM without starting a new transmission sequence. The Full Random Address mode is the most flexible mode of

transmission. The attribute byte is shown in Table 22, and the sequence of transmitted bytes is shown in Table 23. Either another

LSB address & MSB address & attribute & character code or a STOP must follow after each character code.

TABLE 22. Full Random Address Mode

ATTRIBUTE Byte

X

1

1

X

ATT[3:0]

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