GRAPHPAC COMMAND MANUAL Page 7
It is possible to place the CAP on the circumference of a circle after
it has been drawn by using the PLOT command, with the circle radius given as
the plot distance. Obviously the same RATIO value must be used for the PLOT
and CIRCLE commands for the result to be correct.
To alter a single pixel at the CAP co-ordinates dependent on the
current PEN mode.
The following is a BASIC program that follows the actions taken by the
CIRCLE command. Execution is slower as the CIRCLE command is a machine code
subroutine and does not involve any of the overheads associated with a BASIC
10 STARTAT X,Y +: REM THE MIDDLE OF THE SCREEN
20 FOR A=O TO 360
40 PLOT A,R : REM RIS THE RADIUS OF THE CIRCLE
50 PENDOWN : DOCAP : PENRET
60 NEXT A
The CAP command has been added to assist the programmer. It reports
the CAP comordinates, allowing a programs action to be investigated.
CAP reports the co-ordinates on the screen at the current cursor
location in much the same way as a normal print statement.
CAPEK CC RR
CAP® CC,RR reports the co-ordinates on the screen at the specified
CC,RR screen co-ordinates. This action does not effect the cursor address so
that subsequent print statements will act correctly.
GRAPHPAC COMMAND MANUAL Page 8
This reports the CAP co-ordinates on a printer allowing a program’s
action to be investigated.
LCAP will report the CAP co-ordinates to a printer (or the current
LST; device if running under CP/M).
To clear the screen of all graphics and alpha-numeric characters.
GCLR (Graphics Clear)
To clear the screen of graphic characters.
A search is made in the screen memory for any graphic characters. If
any are found they are replaced with a space character. (20 hex.)
CLEOL (CLear To End Of Line)
To clear the display from the current cursor position to the end of
the current line.
To cause scrolling to affect a number of lines (n) on the video
The number of lines specified in the scroll command will be situated
at the bottom of the screen, allowing a display area above to be fixed for
graphics plotting. Alpha-numerics can still be used on the display area with
the use of the SCREEN command. If it is wished to return scrolling to normal,
use the command SCROLL 25. Scrolling will only take place on receipt of a line
feed while the curser is on the bottom line of the display.