Skip to content

Supported functions and statements

Jump to bottom
tt1542 edited this page Jun 2, 2026 · 17 revisions

The following list applies to the 2.0 version and will (hopefully) be updated in the future.

  • REM and apostrophe comments (' comment)
  • LET and implicit assignment without LET
  • INPUT var
  • INPUT "prompt", var
  • INPUT var$
  • INPUT "prompt", var$
  • ! var as shorthand for INPUT var
  • LINE INPUT #channel, var$
  • PRINT
  • ? as shorthand for PRINT
  • PRINT #channel, ...
  • IF ... THEN ...
  • IF ... THEN ... ELSE ...
  • multi-line IF ... THEN, ELSEIF ... THEN, ELSE, END IF
  • GOTO
  • GOSUB
  • RETURN
  • FOR ... TO ... [STEP ...] / NEXT, END FOR
  • WHILE ... / WEND
  • DIM
  • OPEN ... FOR INPUT AS #channel
  • OPEN ... FOR OUTPUT AS #channel
  • CLOSE #channel
  • KILL
  • GET #channel, [position,] variable
  • PUT #channel, [position,] variable
  • CLS
  • LOCATE row, column
  • COLOR foreground, background
  • DEF SEG
  • POKE address, value
  • SELECT CASE, CASE, CASE ELSE, END SELECT
  • RANDOMIZE
  • RANDOMIZE TIMER / numeric-expression
  • XSET handle, index, string-expression
  • XFREE handle
  • END / STOP / . as shorthand

Supported Control Structures

IF / ELSE

BASCOMP supports single-line and multi-line IF forms.

Single-line form:

IF A > 10 THEN PRINT "HIGH" ELSE PRINT "LOW"

Multi-line form:

IF A > 10 THEN
  PRINT "HIGH"
ELSEIF A = 10 THEN
  PRINT "TEN"
ELSE
  PRINT "LOW"
END IF

Boolean IF expressions support AND, OR, and NOT in supported comparison contexts.

SELECT CASE

SELECT CASE supports numeric selection logic:

SELECT CASE A
  CASE 1
    PRINT "ONE"
  CASE 2
    PRINT "TWO"
  CASE ELSE
    PRINT "OTHER"
END SELECT

FOR / NEXT / END FOR

Counted loops are supported, including nested loops and optional STEP values.

FOR I = 1 TO 10 STEP 2
  PRINT I
NEXT I

END FOR is also recognized as an explicit loop terminator form.

WHILE / WEND

WHILE A < 10
  A = A + 1
WEND

Subroutines

Subroutines are supported through GOSUB and RETURN.

Supported Data Types

Numeric Variables

Numeric variables store signed 16-bit integer-style values.

String Variables

String identifiers end with $ and use counted string representation in the runtime.

Indexed Numeric Arrays

DIM creates indexed numeric arrays using syntax such as A(I). Small arrays are stored internally; larger arrays can be backed by external DOS memory through the runtime array support.

DIM A(10)
LET A(1) = 5
LET X = A(1)

External String Arrays

External string arrays are available through:

  • XALLOC(count)
  • XALLOC(count, maxLength)
  • XSET handle, index, string-expression
  • XGET$(handle, index)
  • XFREE handle

Supported Expressions

Numeric Expressions

Numeric expressions support:

  • decimal constants and variables
  • hexadecimal constants with &H...
  • numeric array elements such as A(I)
  • parentheses
  • unary + and unary -
  • +, -, *, /, \
  • MOD
  • XOR
  • AND
  • OR
  • exponentiation with ^
  • numeric function calls

String Expressions

String expressions support:

  • string variables
  • string literals
  • string concatenation with +
  • string function calls
  • DATE$, TIME$, INKEY$, and INPUT$

BASCOMP 2.0 continues the expanded internal string-expression handling introduced before version 2.0. The compiler uses a larger internal string context stack and additional temporary string buffers for nested string functions and concatenations.

Supported Comparisons

The following comparison operators are supported in IF expressions: =, <>, <, >, <=, >=.

Comparisons work for both numeric values and supported string expressions, depending on context.

Supported Functions

Numeric and Conversion Functions

  • LEN(string)
    Returns the length of a string.
  • VAL(string)
    Converts a string to a numeric value.
  • ASC(string)
    Returns the character code of the first character.
  • EOF(channel)
    Returns the end-of-file state for a file channel.
  • EXIST(string)
    Tests whether a file exists.
  • INSTR(string, pattern)
    Searches for a substring and returns its position.
  • INSTR(start, string, pattern)
    Searches for a substring starting at a specific position.
  • ABS(number)
    Returns the absolute value.
  • SGN(number)
    Returns -1, 0, or 1 depending on the sign of the value.
  • RND(number)
    Returns a pseudo-random number in the supported runtime range.
  • INT(number)
    Returns the integer value.
  • SQR(number)
    Returns the integer square root.
  • MIN(a, b)
    Returns the smaller value.
  • MAX(a, b)
    Returns the larger value.
  • TIMER()
    Returns the number of seconds since midnight modulo 65536.
  • EXEC(program$, args$)
    Starts a DOS child program and returns 0 on success or a DOS error code.
  • CPUID()
    Detects the CPU class and returns the runtime CPU identifier.
  • PEEK(address)
    Reads a byte from the active DEF SEG segment.
  • XALLOC(count) / XALLOC(count, maxLength)
    Allocates an external string array and returns a handle.

String-Producing Functions

  • CHR$(number)
    Builds a one-character string from a character code.
  • LEFT$(string, count)
    Returns the left part of a string.
  • MID$(string, start, count)
    Returns a substring.
  • RIGHT$(string, count)
    Returns the right part of a string.
  • LTRIM$(string)
    Removes leading spaces.
  • RTRIM$(string)
    Removes trailing spaces.
  • TRIM$(string)
    Removes leading and trailing spaces.
  • UCASE$(string)
    Converts ASCII lowercase letters a to z to uppercase.
  • STR$(number)
    Converts a numeric value to a string.
  • XGET$(handle, index)
    Reads a string from an external string array.
  • DATE$
    Returns the DOS date in mm-dd-yyyy format.
  • TIME$
    Returns the DOS time in hh:mm:ss format.
  • INKEY$
    Returns a non-blocking keyboard input string.
  • INPUT$
    Reads a string from standard input.

File I/O

Text file I/O is supported through:

  • OPEN
  • CLOSE
  • PRINT #
  • LINE INPUT #

Binary file I/O is supported through:

  • GET
  • PUT

File channels 1 to 9 are supported.

OPEN supports:

  • FOR INPUT
  • FOR OUTPUT

KILL deletes a file. EXIST() checks whether a file is present.

The runtime retains buffered byte output for PUT; buffered binary output is flushed when required by handle changes, seek operations, close operations, and mixed text/binary output paths.

Screen Output

Standard text output is supported through PRINT.

Additional screen control is provided by:

  • CLS
  • LOCATE
  • COLOR

When screen output support is active, runtime text output to the console can use BIOS text output with the active COLOR attribute.

Memory Access

BASCOMP 2.0 supports a compact BASIC-style memory access subset:

  • DEF SEG = expression sets the active segment used by PEEK and POKE.
  • DEF SEG resets the active segment to the program segment.
  • PEEK(address) returns the byte at the active segment and offset.
  • POKE address, value writes a byte to the active segment and offset.

Values written by POKE must fit into a byte (0..255).

Date, Time, Keyboard, EXEC, and CPU Support

BASCOMP 2.0 includes runtime support for:

  • DATE$ using DOS date services,
  • TIME$ and TIMER() using DOS time services,
  • INKEY$ using enhanced BIOS keyboard calls where available,
  • EXEC() for launching DOS child programs,
  • CPUID() for CPU-class detection.

Clone this wiki locally