Atari 800 Basic Reference Manual

SIN
DEGIRAD
SPECIAL
PURPOSE
FUNCTIONS
ADR
FRE
PEEK
POKE
Format:
SIN(aexp)
Example:
100 X = SIN(Y)
Note: Presumes Y previously defined.
Returns the trigonometric sine of the expression in parentheses.
Format: DEG
RAD
Example: 100 DEG
100
RAD
These two statements allow the programmer to specify degrees or radians for
trigonometric function computations. The computer defaults to radians unles s
DEG is specified.
Once the DEG statement has been executed, RAD must be used
to return to radians.
See Appendix E for the additional trigonometric functions that can be derived.
Format:
Example:
ADR(svar)
ADR(A$)
Returns the decimal memory address ofthe string specified by the expre ss ion in
parentheses. Knowing the address enables the programmer to pass th e informa-
tion to USR routines, etc. (See USR and Appendix D)
Format: FRE(aexp)
Examples: PRINT FRE (0)
100 IF FRE (0)<1000 THEN PRINT "MEMORY CRITICAL"
This function returns th e number ofbytes of u ser RAM left. Its primary use is in
Direct mode with a dummy variable (0) to inform the programmer how much
memory space remains for completion of a program. Of course FRE can also be
used within a BASIC program in Deferred mode.
Format: PEEK(aexp)
Examples: 1000 IF PEEK (4000) = 255 THEN PRINT "255"
100 PRINT "LEFT MARGIN IS"; PEEK (82)
Returns the contents of a specified memory address location (aexp). The address
specified must be an integer or an arithmetic expression th at evalua te s to an in -
teger between 0 and 65535 and represe nts the memory addres s in decimal nota-
tion (not hexadecimal) . The number returned will also be a decimal integer with
a ran ge fr om 0 to 255. This function allows the user to examine either RAM or
ROM locat ion s. In the first examp le above , the PEEK is us ed to determine
whether l ocation 4000 (decimal) contains the number 255. In the second exam -
ple, the PEEK function is u sed to examine the left margin.
Format: POKE aexp1, aexp2
Examples: POKE 82, 10
100 POKE 82,
20
Function Li brary 35

Atari 800 Specifications

General

Processor	MOS Technology 6502
Processor Speed	1.79 MHz
ROM	10 KB
Graphics	ANTIC and GTIA chips
Release Year	1979
Display Resolution	up to 320 x 192
Colors	128 colors
Sound	4 channels
Storage	Cartridge, cassette, floppy disk
Ports	Cartridge, serial, monitor
Operating System	Atari OS