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Nothing to it!
NOTE: As long as semicolons are used to delay the line feeds, graphics and text
are easily mixed on the same line. New lines can be started by simply adding
line feeds with PRINT statements as shown in line 140.
The Long Lines Division
None of our examples so far have used the full 480 columns available to the
MX-70. In fact, we've always used less than 100 columns since the printer will
be used by computers with different capabilities. As we expand the widths of
our displays, these differences quickly become more obvious.
TRS-80 type computers, for example, can send a full range of ASCII codes 0 to
255 (8 bits) via the CHR$ function. (A few must be poked, as we've seen.)
These computers can therefore choose any graphics width from 0 to 480
columns.
Printer cards for Apple type computers typically pass ASCII numbers from 0 to
127 (7 bits). This forces us into extra programming and devious means to utilize
the MX-70's complete range of 480 graphics columns.
In any one <ESC>"K" sequence, 7-bit computers are restricted to the ranges
O-127 and 256-383. Seeing is believing, so:
DELETE lines 150-200, and add:
150 DATA 150,-150,127
and RUN.
Here's what happened. The 150 cannot be passed, so is reduced by 128, and
sent to the printer as 22. Apple users see a bar 22 columns long (did you count
them?). Users with 8-bit computers see a bar 150 columns long.
Figure 7-4
Figure 7-5
The Final Push
61
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