System Specification for C65 | Fred Bowen | March 1, 1991 |

### 3.1.3 __BASIC 10.0 COMMAND AND FUNCTION DESCRIPTION__

#### ABS - Absolute value function

ABS (expression)

The ABSolute value function returns the unsigned value of the numeric
expression.

X = ABS (1) Result is X = 1
X = ABS (-1) Result is X = 1

#### AND - Boolean operator

expression AND expression

The AND operator returns a numeric value equal to the logical AND of
two numeric expressions, operating on the binary value of signed
16-bit integers in the range (-32768 to 32767). Numbers outside this
range result in an 'ILLEGAL QUANTITY' error.

X = 4 AND 12 Result is X=4
X = 8 AND 12 Result is X=8
X = 2 AND 12 Result is X=0

In the case of logical comparisons, the numeric value of a true .
situation is -1 (equivalent to 65535 or $FFFF hex) and the numeric
value of a false situation is zero.

X = ("ABC"="ABC") AND ("DEF"="DEF") Result is X=-l (true)
X = ("ABC"="ABC") AND ("DEF"="XYZ") Result is X= 0 (false)

#### APPEND - open a disk file and prepare to append data to it

APPEND# logical-file-number, "filename" [,Ddrive] [<ON|,>Udevice]

Opens filename for writing, and positions the file pointer at the end
of the file. Subsequent PRINT# statements to the logical file number
will cause data to be appended to the end of this file. If the file
does not exist, it will be created.

APPEND#1, "filename"
APPEND#1, (file$), ON U(unit)

#### ASC - PETSCII value function

ASC (string)

This function returns the PETSCII numeric value of the first character
of a string. The PETSCII value of an empty (null) string is zero.
This function is the opposite of the CHR$ function. Refer to the
Table of PETSCII Character Codes.

X = ASC("ABC") Result is X=65
X = ASC("") Result is X=0

#### ATN - Arc tangent function

ATN (expression)