LM1237BDKENANOPB National Semiconductor, LM1237BDKENANOPB Datasheet - Page 23

• Manufacturer Part Number: LM1237BDKENANOPB
• Manufacturer: National Semiconductor

Specifications of LM1237BDKENANOPB

• Operating Temperature (min): 0C
• Operating Temperature (max): 70C
• Operating Temperature Classification: Commercial
• Mounting: Through Hole
• Package Type: MDIP
• Lead Free Status / RoHS Status: Compliant

Two-Color Attribute Table
Note: Set reserved bits to 0.
The attributes for two-color display characters may be written or read via the following address format:
A15–A6: Always a binary 1000010001.
A5–A2: Attribute code n (0x0–0xF are valid values).
A1–A0: Determines which of the 3 bytes is to be accessed.
Note: In the table, n indicates the attribute number 0 ≤ n ≤ 15.
Note: When writing, bytes 0 through 2 must be written in order. Bytes 0 through 2 will take effect after byte 2 is written. Since byte 3 contains all reserved bits, this
When reading, it is OK to read only one, two, or all three bytes.
If writing more than one 2-color attributes using the auto increment feature, all four bytes must be written.
Four-Color Attribute Table
Note: Set reserved bits to 0.
The attributes for four-color display characters may be written or read via the following address format:
A15–A7: Always a binary 100001010.
A6–A3: Attribute code n (0x0–0xF are valid values).
A2–A0: Determine which of the six bytes of the attribute is to be accessed.
Note: In the table, n indicates the attribute number 0 ≤ n ≤ 15.
Note: When writing, bytes 0 through 2 must be written in order and bytes 4 to 6 must be written in order. Bytes 0 through 2 will take effect after byte 2 is written.
When reading, it is OK to read only one, two, or all three bytes.
If writing more than one 4-color attributes using the auto increment feature, all eight bytes must be written.
Display Page RAM
THE OSD WINDOW
The Display Page RAM contains all of the 8-bit display
character codes and their associated 4-bit attribute codes,
and the special 12-bit page control codes — the row-end,
skip-line parameters and window-end characters.
The LM1237 has a distinct advantage over many OSD gen-
erators that it allows variable size and format windows. The
window size is not dictated by a fixed geometry area of RAM.
CHARACTER CODE AND ATTRIBUTE CODE
Each of the 512 locations in the page RAM is comprised of a 12-bit code consisting of an 8-bit character or control code, and a
4-bit attribute code:
ATT2C1n
ATT2C2n
ATT2C3n
ATT4C0n
ATT4C1n
ATT4C2n
ATT4C3n
ATT4C4n
ATT4C5n
ATT4C6n
ATT4C7n
Register
Register
byte may be written, but will have no effect.
Bytes 4 through 6 will take effect after byte 6 is written. Since bytes 5 and 7 contain all reserved bits, these bytes may be written, but no effect will result.
Address
Address
8500 +
(n*8)
+1
+2
+3
+1
+2
+3
+4
+5
+6
+7
C2B[0]
C2B[0]
C4B[0]
D7
D7
TABLE 8. LM1237 Two-Color Attribute Registers (Continued)
X
X
X
X
X
X
C1B[1:0]
C3B[1:0]
TABLE 9. LM1237 Four-Color Attribute Registers
D6
D6
X
X
X
X
X
X
(Continued)
C2G[2:0]
C2G[2:0]
C4G[2:0]
D5
D5
X
X
X
X
23
C1G[2:0]
C3G[2:0]
Instead, 512 locations of 12-bit words are allocated in RAM
for the definition of the windows, with special control codes
to define the window size and shape.
Window width can be any length supported by the number of
pixels per line that is selected divided by the number of
pixels in a character line. It must be remembered that OSD
characters displayed during the monitor blanking time will
not be displayed on the screen, so the practical limit to the
number of horizontal characters on a line is reduced by the
number of characters within the horizontal blanking period.
D4
D4
X
X
X
X
EF[3:0]
EF[3:0]
D3
D3
X
X
X
X
C2R[2:0]
C2R[2:0]
C4R[2:0]
D2
D2
X
X
X
X
C1R[2:0]
C3R[2:0]
D1
D1
X
X
X
C2B[2:1]
C2B[2:1]
C4B[2:1]
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C1B[2]
C1B[2]
C3B[2]
D0
D0
X
X
X