Specifications

EPSON 9–21
SED1278
SED1278
THE CHARACTER GENERATOR
Character Generator ROM (CGROM)
The SED1278 contains a 240 character, masked CGROM.
Each character is 5×10 pixels, for 1/11 duty cycle
compatibility. Refer to Appendix A for available codes
and their corresponding fonts.
Because the CGROM is masked, customers may arrange
to have their own CGROM masks made.
A custom mask allows the user to have
• their own character set.
• a character set of up to 256 characters.
Please contact the SEIKO EPSON Marketing Department
for further information.
If a custom CGROM is used, two things should be noted.
1. The “Clear Display” instruction relies on the character
whose code is 20H being a blank.
2. If more than 240 ROMed characters are specified,
then the number of CGRAM characters available is
correspondingly reduced. The physical RAM space is
still available, and is available for use as memory,
however it will no longer have an associated character
code.
3. The character ROM implemented in a particular chip
is indicated by a two character suffix attached to the
device number, for example SED1278F
0A.
Character Generator RAM (CGRAM)
The SED1278 has 64 bytes of CGRAM, allowing the
user to program up to 8 characters.
5×8 pixel font (1/8 or 1/16 duty cycle)
The maximum character height is 8 pixels, however if a
cursor is used row 7 should be all zeros. 8 such characters
are available to the user.
The CGRAM address is made up of the following
components.
• The least significant three bits,
a2 to a0, specify the
row number of the character data.
• Bits
a5 to a3 are made up of the least significant three
bits of the character code.
• The most significant bit,
a7, is ignored.
Figure 1 shows an example 5×8 pixel font.
Figure 1 A 5×8 Pixel Font
CGRAM address
CGRAM data
(Character pattern)
A5····A0DB7······DB0
000000* * *00001
000001* * *00001
000010* * *01001
000011* * *11111
000100* * *01000
000101* * *00000
000110* * *00000
000111* * *00000