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72 lines
1.9 KiB
Plaintext
Executable File
72 lines
1.9 KiB
Plaintext
Executable File
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ARDS GRAPHICS
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ARDS uses an ASCII character to enter one of three graphics, remains
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in that mode for 2 or 4 characters of argument, then stays in that mode
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until explicitly changed to another mode.
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The modes are as follows:
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MODE args octal ctl comment
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character - 34 ^\ leave graphics mode *
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set-point 4 35 ^] absolute coordinates
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long-vector 4 36 ^^ relative, visible/invisible,
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solid/dotted
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short-vector 2 37 ^_ visible vectors only
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Notes:
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* Character mode is entered by receipt of any ASCII "control"
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character, and the control function (eg CR, FF) is also executed.
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An ARDS does not have a control function associated with the ASCII
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character 34 (GS, ^\)
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** short vectors are nice "fast" ways of doing curves, especially over
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slow TTY lines.
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Argument characters are in the range 100 <_ a <_ 177 (@ to DEL)
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SETPOINT ABSOLUTE FORMAT
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--35-- --x1-- --x2-- --y1-- --y2-- --**--
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X and Y coordinate information are sign-magnitude numbers
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x1, y1 are the low order bits; x2, y2 are high order bits
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x1 = < |X| & 37 > _ 1 <ifl x, + 1> + 100
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2i.e: shift left 1; if < 0 add 1; then add 100
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x2 = < |X| _ -5 > & 37 + 100
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y1 like x1
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y2 like x2
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** since setpoints do not plot, it is not useful to stay in setpoint
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mode - this should be followed by an escape to character mode, or one
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of the vector modes.
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LONG-VECTOR RELATIVE FORMAT
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--36-- --x1-- --x2-- --y1-- --y2-- --...--
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x1, y1 are like setpoint, only they specify relative coordianates
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instead of absolute
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x2 ditto, + if invisible then 40
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y2 ditto, + if dotted then 40
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... additional groups of four characters follow, doing more vectors,
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until a control character comes.
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SHORT-VECTOR RELATIVE FORMAT
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--37-- --x1-- --y1-- --...--
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x1, y1 are like setpoint
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note that only the low order character is sent for short vector, so
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"invisible" or "dotted" may not be specified.
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note |x|, |y| < 40 (8)
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