User`s manual

8-1
8 / Special Features
LEVEL II BASIC offers some unusual functions 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. Other functions in the chapter
are of obvious benefit and will be used often (for example, the
graphics functions). And then there are a couple of features,
INP and OUT, that will be used primarily with the TRS-80
Expansion Interface.
Functions, statements and operators described in this chapter:
Graphics:
Error-Routine
Functions:
Other Functions
and Statements:
SET ERL INP
RESET ERR MEM
CLS OUT
POINT
Logical Operators:
PEEK
POKE
AND POS
OR USR
NOT VARPTR
SET
(x,y)
Turns on the graphics block at the location specified by the coordinates x 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 upper left of the Display, while the point at
(127,47) is in the extreme lower right corner. See the Video Display
Worksheet in Appendix C.
The arguments x and y may be numeric constants, variables or expressions.
They need not be integer values, because SET(x,y) uses the INTeger portion
of x and y. SET (x,y) is valid for:
0<=x<128
0<=y<48