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Gemini User's Manual
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ing notes, you should be able to run all the sample programs
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presented in this manual if you use Applesoft BASIC.
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Applesoft BASIC uses the PRINT command to send informa-
tion to both the screen and the printer.
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The PR # 1 command sends the information only to the printer
(when the printer interface is in slot number 1), and the PR # 0 com-
mand sends the information only to the screen.
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Therefore, you should use:
PRINT
CHR$(4)
"PR#1"
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PRINT
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instead of the LPRINT command. In addition, use:
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PRINT
CHR$(4)
"PR#O"
PRINT
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instead of the PRINT command.
The Apple video display is 40 columns wide. If you want the
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print mode to print more than 40 columns, you need to send an
additional command code:
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PRINT
CHR$(4)
"PR#1"
PRINT
CHR$(9)
"255N"
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PRINT
This message allows Gemini to print a line of any length. This is
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particularly important when sending bit-image graphics to Gemini.
The CHR$(9) (or function code HT, which moves the print
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head to the next tab position) and CHR$(13) (or function code CR
for a carriage return) codes cause problems when used in both the
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Gemini escape-function code sequences and in the graphics
mode. Avoid using these codes if possible.
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The printer interface card does not allow us to send ASCII
codes greater than 127. If you try to send these codes, the inter-
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face sets the eighth bit to zero. The result, for example, is that
PRINT CHR$(239) would be received by the printer as PRINT
CHR$(111); that is, 239 -128
=
111. Gemini provides the ESC"
>"
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function code to allow 7-bit interface users to overcome this prob-
lem. See Chapter 9 for a discussion of this problem.
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Apple users (and other 7-bit interface users) should also be
aware of the difference between 7-bit and 8-bit interface graphics.
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See Chapter 6 for a discussion on this topic.
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