Language guide

• Working with programs
• Control flow
• Arrays and variables
• Type conversion
• String operations
• Text and the screen
• The printer
• Keyboard input
• Function-key macros
• Calculations and maths
  • Mathematical functions
  • Random numbers
• Devices and files
  • File operations
  • Devices
• Graphics
• Sound
• Joystick and mouse
• Disks and DOS
• Serial communications
• Event handling
• Error handling
• User-defined functions
• Date and time
• Including data in a program
• Memory and machine ports
• Features not yet implemented
• Unsupported features

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This documentation describes the SE Basic IV language, which aims to support programs written for Microsoft BASIC with minimal changes.

The Language Guide covers the language topic by topic, thematically grouping language elements used for a related purpose. Refer to the Language reference for a formal description of the language elements and their syntax.

Working with programs

Statement	Description
AUTO	Enter automatic line numbering mode
CHAIN	Load a new program and run it, preserving common variables
DELETE	Delete lines from the program
EDIT	Print a program line to the screen for editing
LIST	Print program lines to the screen
LOAD	Read a new program from file
MERGE	Overlay a program file onto the current program
NEW	Clear the current program from memory
RENUM	Replace the program's line numbers
RUN	Start the current program
SAVE	Store the current program to file
TRON	Enable line number tracing
TROFF	Disable line number tracing

Control flow

Statement	Description
CONT	Continue interrupted program
ELSE	Ignore the remainder of the line (standalone ELSE)
END	Stop execution of the program
FOR	Start a for-loop
GOSUB	Call a subroutine
GOTO	Jump to another location in the program
IF	Branch on a condition
NEXT	Iterate a for-loop
ON	Calculated jump or subroutine call
RETURN	Return from subroutine
STOP	Interrupt program execution
WEND	Iterate a while-loop
WHILE	Enter a while-loop

Arrays and variables

Statement	Description
DIM	Allocate an array
ERASE	Deallocate an array
SWAP	Swap two variables

Type conversion

Function	Description
ASC	Character to ordinal value
CHR$	Ordinal value to character
HEX$	Integer to hexadecimal string representation
OCT$	Integer to octal string representation
STR$	Numeric value to decimal string representation
VAL	String representation to numeric value

String operations

Function	Description
LEN	String length

Text and the screen

Statement	Description
CLS	Clear the screen
COLOR	Set colour and palette values
LOCATE	Set the position and shape of the text screen cursor
PALETTE	Assign a colour to an attribute
PALETTE USING	Assign an array of colours to attributes
PRINT	Print expressions to the screen

Function	Description
SCREEN	Character or attribute at given location

The printer

Statement	Description
PRINT #	Print expressions to the printer

Keyboard input

Statement	Description
INPUT	Retrieve user input on the console
LINE INPUT	Retrieve a line of user input on the console

Function	Description
INKEY$	Nonblocking read from keyboard
INPUT$	Blocking read from keyboard

Function-key macros

Statement	Description
KEY	Define a function-key macro

Calculations and maths

Mathematical functions

Function	Description
ABS	Absolute value
ATAN	Arctangent
ACOS	Arccosine
ASIN	Arcsine
COS	Cosine
EXP	Exponential
FIX	Truncation
INT	Floor
LOG	Natural logarithm
SIN	Sine
SGN	Sign
SQR	Square root
TAN	Tangent

Random numbers

Statement	Description
RANDOMIZE	Seed the random number generator

Function	Description
RND	Pseudorandom number

Devices and files

File operations

Statement	Description
CLOSE	Close a file
INPUT	Read a variable from a file
OPEN	Open a data file

Function	Description
EOF	End of file
LOC	Location in file
LOF	Length of file
INPUT$	Read a string from a file

Devices

SE Basic IV handles devices differently than Microsoft BASIC. A device is connected to a specific channel and one or more I/O streams can be connected to that channel. For example, the display is connected to channel S and by default stream #2 is connected to that channel S.

Device	Channel	Default stream
Keyboard	K	1
Screen	S	2

Graphics

Statement	Description
SCREEN	Change the video mode

Sound

Statement	Description
SOUND	Generate a tone

Joystick and mouse

Function	Description
MOUSE	Status of mouse
STICK	Status of joystick

Disks and DOS

In SE Basic IV, the DOS is integrated into BASIC and there is no SHELL command.

Statement	Description
CHDIR	Change current directory.
COPY	Make a copy of a file.
FILES	List the files in the current directory.
KILL	Delete a file on a disk device.
MKDIR	Create a new directory.
NAME	Rename a file on disk.
RMDIR	Remove a directory.

Serial communications

Event handling

Error handling

Statement	Description
ERROR	Raise an error
ON ERROR	Define an error handler

User-defined functions

Statement	Description
DEF FN Define a new function

Function	Description
FN	User-defined function

Date and time

Including data in a program

Statement	Description
DATA	Define data to be used by the program
READ	Retrieve a data entry
RESTORE	Reset the data pointer

Memory and machine ports

Only selected memory ranges are accessible in SE Basic IV. There is read and write support for video memory, font RAM and selected locations of the low memory segment, including the keyboard buffer. Additionally, there is read and write support for variable, array and string memory. Writing into the program code is permitted but not recommended. All ports including keyboard input and video modes are supported.

Statement	Description
BLOAD	Load a binary file into memory
BSAVE	Save a memory region to file
CLEAR	Clears BASIC memory
DEF SEG	Set the memory segment
OUT	Write a byte to a machine port
POKE	Write a byte to a memory location

Function	Description
FRE	Amount of free memory
INP	Byte at machine port
PEEK	Byte at memory address

Features not yet implemented

Some documented features are not yet implemented. They may be added in a future release.

Unsupported features

SE Basic IV has direct access to all areas of memory and all devices. You can use machine-code subroutines to perform tasks for which it does not provide support. However, programs written for a different architecture, such as 8086, will not run.

It is not necessary, or possible, to define variable types. Like the 6502 versions of Microsoft BASIC, floating-point numbers are always stored in 40-bit MBF form. Unlike Microsoft BASIC, integers in the range -65536 to 65535 are always stored as integers (also in 40-bits).