TINY BASIC SUMMARY
 
Editing		Standard Basic
 
Direct Mode	All Verbs Usable
 
Statement Types
 
	PRINT	Item List
	LET	Var = Expr	(LET is optional)
	IF	Expr Relop Expr  Statement
	INPUT	Variable List
	GOTO	Line Number
	GOSUB	Line Number
	RETURN
	POKE	POKE(Expr) = Expr
	STOP
	LIST	Line Number, Line Number	(Line Numbers are optional)
	RUN
	NEW
 
Functions
 
	USR	Variable = USR(Expr,Expr)
	PEEK	Variable = PEEK(Expr)
	MEM	Variable = MEM
 
Number		Integers to _+32767 or Hex Integers preceded by a $ symbol
 
Variable	Letters A-Z
 
Expression	Variables, Numbers, and Functions combined with the following
		operators +, -, *, /, (, ).
 
Relop		Comparison operators =, <, >, <=, >=, <>.
 
Line Number	Numbers 1 through 9999
 
String		"ALPHANUMERICS"
 
Item List	Expressions and Strings seperated by format control
		characters , and ;.
 
Control Chars.	Control H or "Back Space" deletes last input character.
		Control X or "Cancel" deletes entire input line.
		Control C Terminates Basic program or List operation and
			  returns control to command mode.
 
Memory Usage	Tiny Basic V1.37
 
$0080 - $009F	Tiny Basic interpreter scratch area.
$00A0 - $00FD	Not used by Tiny Basic interpreter. (usable USR routines)
$**** - $****	Pointer to Interrupt Vector Table. (Identical to LILBUG)
$D800 - $DFFF	Input Buffer, Basic Program storage, Stack Space, and
		Variables in RAM.
$**** - $****	Optional Power Up Basic Program and/or USR functions in ROM.
$E800 - $EFFF	Tiny Basic interpreter ROM.
 
$E800		Cold Start Address.
$E803		Warm Start Address.

			Tiny Basic USR Function
 
The USR function in Tiny Basic takes 2 arguments and returns a value to a
variable. The form of the USR function is "LET V = USR(Expr,Expr)".
The USR function can be used in any expression in Tiny Basic as an example
"LET V = A * ( B + USR( $EF00, K))". The USR function can also be used with
the PRINT statement.
 
The first argument of the USR function is evaluated to determine the address
or the machine language code to be called. The second argument is evaluated
and the value is send to the machine code routine in the D accumulator. The
second argument is optional, if it is present the Carry bit in the condition
code register will be cleared when the machine code routine is called. If the
second argument is not present the Carry Bit will be set when the machine code
is called. The machine code routine may return a result to the BASIC program
in the D accumulator, the value in the D accumulator on return from the machine
code routine will be used by the BASIC program as the value of the function.
 
The machine code routine must execute a RTS instruction to return conterol to
the BASIC program. The machine code routine may use all the processor registers
freely and need not save and restore any registers. It is important that the
machine code routine not modify any memory used by the Tiny Basic interpreter.
Consult the memory map provided with your version of Tiny Basic to determine
which memory areas are not used.
 
Tiny Basic handles interrupts with the same interrupt vectoring technique used
by LILBUG. Consult the LILBUG manual for details on interrupt vector usage.
 
 
 
							JPB  12-APR-82