Compuprint 9058 Programmer Manual - Manual (Page 52)

EPSON/IBM Mode
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- Bit 5 to 0 These 6 bits indicate the effective number of dot
columns of the character shape stored in memory.
Byte 4:
- Bit 7, 6 Graphic character description:
- 0: shading character
- 1: line drawing character
- 10: underscored character
- 11: not supported
All graphics characters are 30 dot high. An
underscored character is defined as a blank graphic
(all zeros) and it is automatically generated by the
printer. A shading character repeats dots 1-6 of each
column as dots 25 through 30 respectively. A line
drawing character repeats dots 23 and 24 as the pairs
25 and 26, 27 and 28, 29 and 30.
- Bit 5 to 0 The number of dot columns of the character shape
minus one. For example: the character width of Draft
generator is 10 dots and bit 5 to 0 must be set to 9.
- Bit 5 to 9 Compression mask description. It is used to optimize
the memory occupation and it is based on the concept
that a dot column on its left is not stored. You can
calculate the compression mask of a character only
after designing the entire character. Every bit is
associated with a dot column with the bit 7 of byte 5
associated with the leftmost column. The bit is set to
1 if the column is equal to the preceding one;
otherwise, it is set to 0. If the character is longer than
39 dot columns the remaining dot columns must be
stored without compression. The bit 40 (bit 0 of byte
9) must be 0. If no compression is present in the
character, byte 5 to 9 is composed by all zeros.