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Of course, many more facilities are available with the printer, but this may
give you some ideas as to how you can drive the printer using your own
programs.
Patches necessary to use the BASIC interpreter
When using the Microsoft BASIC interpreter usually supplied with PCs and
compatibles, a number of problems may arise. Firstly, if the interpreter
transmits a carriage return (ODh) character to the printer, it automatically
transmits a line feed as well. Secondly, the BASIC interpreter will not
transmit EOF markers (1Ah) at all. Normally, this will not cause problems,
but if such a character is included in a character definition or graphic data
string, problems may occur. To get round these two problems, the use of the
following subroutine patches is recommended:
3090
GOSUB 5000
Monochrome display
5000
'
5010
O=INP(&H3BD)
:IF
0<128
THEN 5010
5020
OUT &H3BC,MM :OUT LH3BE.5
:OUT &H3BE,4
5030
RETURN
Color display
5000
'
5010
O=INP(&H379)
:IF
O<l28
THEN 5010
5020
OUT &H378,MM
:OUT &H37A,5
:OUT &H37A,4
5030
RETURN
Call these subroutines when downloading characters or bit-image data,
instead of using an LPRINT CHR$(MhJ) statement. For other languages,
check the documentation to see how the compiler/interpreter handles end-
of-line and end-of-file characters.
NOTE
These patches are only for use with Microsoft BASIC interpreters underPC-DOS
or MS-DOS on PCs/PC-ATs or compatibles. They will not work with other
languages, machines and/or operating systems.
96
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