User`s manual

8-7
We can use POKE to turn on the entire PRINT position (6 bits) at one time.
When we use SET, only 1 bit is turned on. Therefore POKE is about 6 times
faster than SET. The following program demonstrates this speed.
10 CLS
20 FOR X=15360 TO 16383
30 POKE X,191
40 NEXT
50 GOT0 50
RUN the program to see how fast the screen is "painted" white. (191 is the
code for "all bits on". 15360 to 16383 are the Video Display memory
addresses.)
Since POKE can be used to store information anywhere in memory, it is very
important when we do our graphics to stay in the range for display locations.
If we POKE outside this range, we may store the byte in a critical place. We
could be POKEing into our program, or even in worse places like the stack.
Indiscriminate POKEing can be disastrous. You might have to reset or power
off and start over again. Unless you know where you are POKEing - don't.
See
PEEK, USR, SET,
and Chapter 4, CHR$ for background material.
POS
(x)
Returns a number from 0 to 63 indicating the current cursor position on the
Display. Requires a "dummy argument" (any numeric expression).
100 PRINT TAB(40) POS(0)
prints 40 at position 40. (Note that a blank is inserted before the "4" to
accommodate the sign; therefore the "4" is actually at position 41.) The "0" in
"POS(0)" is the dummy argument.
100 PRINT "THESE" TAB(POS(0)+5)"WORDS" TAB(POS(0)+5)"ARE";
110 PRINT TAB(POS(0)+5)"EVENLY" TAB(POS(0)+5)"SPACED"
RUN
THESE WORDS ARE EVENLY SPACED
READY
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