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The Data Bank
HI RESolution graphics requires lots of DATA. It comes with the territory
So, what should our DATA lines look like? How should we format them so
contain the information we need? What information do we need?
ASCII numbers O-127 are used to specify the firing combinations for the 7 pins.
Since much graphic printing, fortunately, is repetitious, we can develop a
coding scheme to simplify and reduce the sheer volume of DATA required. It
can use pairs of numbers.
To avoid needless typing, let's use a minus sign as a "flag" for the first of the
number pair to indicate that its value tells the number of times something is to
be repeated. The second value of the pair will specify the desired combination
of pins to be tired. For example:
100 DATA -42,127
means: "fire all 7 pins (#127) 42 times." Think that one through before con-
tinuing.
Got it?
We also have to tell the printer the number of columns to print on each line.
Let's dedicate the first number in each DATA line to that purpose.
Enter this line of DATA:
1 0 2 0
D A T A
5 5 , 0 , 3 , 7 , 1 5 , 3 1 , 6 3 , 6 3 , - 4 2 , 1 2 7 , 6 3 , 6 3 , 3 1 , 1 5 , 7 , 3
Recheck the numbers carefully to be sure they are copied correctly.
The first number tells the MX-70 to expect 55 bytes of graphic information. The
rest of the numbers specify the pin combinations to be fired in each column,
except for that suspicious number pair in the center: -42,127. Remember what
it means?
The Program
We also need a "DO LOOP" that will READ the DATA:
Advanced Graphics
they
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