16
Accepted" transition and responds by allowing the program to output the next
sequential ASCII character.
To set the printer's line width adjustment, you should use Mikbug to change
the data in memory locations A056 and A065 from 0D16 to 0016. This will eliminate
the transmitted carriage returns and force the printer to print a full 40 column
line. The line width control should then be adjusted for symmetrical margins. The
characters will still be printed sequentially but will not be identical from line
to line.
DO NOT operate the printer more than a minute or so while running this
diagnostic. Continuous printing of full length lines with no spacing between
characters overheats the solenoids on the print mechanism which may decrease its
operating life.
If you are using the SWTPC PR-40 printer with the SWTPC 6800 Computer
System, you may use the OUTCHR subroutine listed from address A014 thru A024 in
the PRNTST diagnostic within your own program for outputting characters to the
printer. The index register must be loaded with the starting address of the MP-L
Parallel Interface board feeding the printer. The character to be printed must be
loaded into accumulator A and the contents of accumulator B are destroyed during
the subroutine.
Never install or remove the interface board when the system is powered up.
Doing so is not only hazardous to the equipment, but bypasses the normal power-up
sequence required by the internal registers within the 6820 integrated circuit in
order to guarantee proper operation.
Mikbug is a registered trademark of Motorola Inc.