8/SpecialFeatures
ModelIII
BASIC
offers some unusualfunctions
and
operations that deserve special
highlighting.
Some
may seem highly specialized; as you learn more about
programming
and
begin to experiment with machine-language routines, they will
take on more significance. Otherfunctions in the chapterare
of
obvious benefit
and
will be
used
often (for example, the graphicsfunctions).
Functions, statements
and
operators described in this chapter:
Graphics:
SET
RESET
CLS
POINT
SET(x,y)
Error-
Routine
Functions:
ERL
ERR
OtherFunctions
and Statements:
INP
MEM
OUT
PEEK
POKE
pas
USR
VARPTR
Turns
on
the graphics block at the location specified by the coordinatesx and y. For
graphics purposes, the Display is divided up into a 128 (horizontal) by 48 (vertical)
grid.
The
x-coordinates are numbered from left to right, 0 to 127.
The
y-coordinates
are numbered
from
top to bottom, 0 to 47. Therefore the point at (0,0) is in the
extreme upperleft
of
the Display, while the pointat (127,47) is in the extreme
lowerright
comer.
See
the Video Display Worksheet in the Appendix.
The
argumentsx
andy
may
be numeric constants, variables
or
expressions. They
need not
be
integervalues, because SET(X,y) uses the INTeger portion
of
x
andy.
SET
(x,y) is valid for:
0<
=x<128
0<=y<48
8/1
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