ATOM PASCAL         versie 1.1986

Inhoud Text in / output Reserverd Words Keywords

Standard Identifiers Functions and Operators Error diagnostics Nederlandse tekst

Na het laden wordt het programma opgestart met link #3000. De Prompt is een pijltje naar links, hier voorgesteld met <-   . LINK#3000 PROMPT: <- PROGRAM: #3000- #7FFF WORKING AREA: #06 tot #FF, #200 tot #2FF USER AREA: #8200- #97FF: ( zie onderverdeling hiernaast) TEXT <T Top line position <B Bottom line position (-.-) <N/n Next n lines (“."=all,RTN=1) <U/n Up n lines <F Find line containing string <? string IN / OUT <R Read text from keyboard ? <L/n List n lines TV/printer <C COS/DOS (To ATOM COS/DOS) SAVE"FILE" *LOAD"FILE" Back to PASCAL = Control P (Useless after BREAK) TOGGLE <A Assignment tracing. Print values changed by Assignment and FOR statements. <S Statement tracing. Print text unit just before it is executed.

EDITING 
<D/n 	Delete n lines 
<I 	Insert one line ahead of current line 
? 
<SP 	(SP=SPACE) List current line 
<V 	View 5 lines 

EXECUTION 
<G 	GO, execute program 
<K 	Check program syntax 
<, 	Execute and trace program . 
<X 	Execute immediately one statement ( STM )
?STM

<P 	Page, redefine number of printer columns ( decimal ) .RTN=64 (default)
<M 	Show number of free user- memory bytes ( decimal )
<Z 	Delete program ( cold start) N or SPACE = NO, Y = YES
<E 	End PASCAL, back to BASIC. (BREAK
<ESC 	Stop 

ATOM PASCAL is both a compiler and an interpreter. It compiles source statements written in Pascal directly from the keyboard into an internal format. The internal format contains both the object code to be interpreted upon execution and source code identifiers for formatted printout to support editing at the source code level. Indentation levels are set automatically to aid debugging. The object code (program) can be saved and loaded on tape or disk. (Starting address of code in address #97B2/B3). Input lines must be restricted to 50 characters. Machine-code subroutines can be called using SUBR(CALL) or FUNC(CALL). These subroutines must not contain operating system vectors (#200-#21B):

PROGRAM BLEEP;

VAR BLEEP=$FD1A:CHAR;

BEGIN

SUBR(BLEEP) (or WRITE(FUNC(BLEEP) ))

A well known textbook in Pascal is “Pascal User Manual and Report". Springer Verlag (1978) by Jensen and Wirth. Most of these Standard Pascal features are implemented:

Constants: 	FALSE 	TRUE
 
Types: 		BOOLEAN 	CHAR 	INTEGER 
		REAL	STRING	TEXT 


Functions: 	ABS 	FUNC 	ROUND 	SUCC 
		ARCTAN	LN 	SIN 	TRUNC 
		CHR 	ODD 	SQR 
		COS 	ORD 	SQRT 	
		EXP 	PRED 	SUBR 

Procedures: 	READ 	READLN 	WRITE 	WRITELN 
		BREAK 


Character Functions:

Word 	Function		Operand(s)	Result
CHR	Character		Integer		Character
ORD	Ordinal 		Scalar except Real	Integer 
PRED 	Predecessor 	Scalar except Real 	Same as Operand
SUCC	Successor		Scalar except Real 	Same as Operand


Machine Language Functions:

Word 	Function		Operand(s)	Result
SUBR	Subroutine Call	Address		-
FUNC	Function Call	Address, Data	Char 

Arrhythmic Operators
 
Symbol/Word 	Operation 
+ 		Addition (plus sign)
-		Subtraction (minus sign)
*		Multiplication 
/ 		Division 
DIV		Division (yields a truncated integer result) 
MOD 		Modules (yields the remainder of division)
 
Relational Operators 

Symbol/Word 	Operation
>		Greater than 
>= 		Greater than or equal to
< 		Less than 
<=		Less  or equal to
=		Equal to
<>		Not equal to 

EXECUTION TIME DIAGNOSTICS 

The form of the diagnostic message is . 

	ERROR *nn
	text unit

After control returns to the command interpreter, a series of WRITELNs may be executed with the <-X command to examine the state of the data. The position of the text unit pointer insures that visibility of identifiers is the same as that which prevailed at the time of the error. The data structures build during execution are not initialized until the next <-G or <-, is executed, so data are available for examination.

In the case of the syntax error message. the right-most "*" usually gives a strong clue about the error, since the character immediately to its right is the one which led the syntax analyzer into the impasse. If the right-hand "*" is the last. character of the diagnostic message, something is m1missing at the end of the input, for example, a final semicolon in a declaration or definition.

Note: 	Error numbers with an asterix are internal checks. 
	Their occurrence may indicate loss of memory integrity.
 
01*
02*
03	Value Stack has exceeded available space.
04*
05* 
06 	Too few actual parameters 
07 	Too many actual parameters 
08	Actual parameter of a VAR formal parameter is an expression
09*	
10 
11	Ordinal type where ordinal ( scalar) type required.
12	Maximum permissible dynamic statement depth of 24 exceeded. 
13*	Ordinal value computation out of range (Array and set selection)
14* 
15* 
16 	Expression result type should be Boolean and is not. 
17 	Function identifier on left-hand side of assignment does not refer 
	to a declared function.
18* 
19	Type compatibility error in assignment or actual value parameter.
20 	Type (s) improper for operator.
21 	Attempt to make array selection on a nonarray. 
22 	String length excessive for operation.
23	Empty string improper for operation 
24*	
25 	Attempt to negate a nonnumeric. 
26	Operand should be Boolean.
27*
28	GOTO with destination textual depth greater than that of GOTO.
29	Actual/formal parameter type discrepancy. 
30	Control variable has changed in FOR loop.
31	Argument of CHR not in 0. .255.
32	Value less than lower limit of subrange.
33	Value greater than upper limit or subrange.
34	Argument not ordinal (scalar).
35	Argument not real or integer. 
36 	GOTO refers to an undefined label. 
37 	Actual/formal VAR parameter type discrepancy. 
38 	Array reference to STRING with noninterger subscript. 
39 	Right operand of IN not a set or packed set. 
40 	Source String to long for receiving string. 
41	Improper argument of record select ( .) operator. 
42* 
43	No match between value of expression and CASE constants. 
44 	Argument of WITH is not a record variable. 
45 	More than the maximum of 16 records in a program. 
46	Field identifier not preceded by “.”  and not in the scope of a WITH.
47* 
48 	Processor stack pointer is higher than when break discontinued	
	execution: Break-in-progress is now false and <-G will start at beginning. 
49 	Processor stack is about to overflow.
50 	Attempted division by zero.
51 	Floating-point overflow. 
52	Fixed-point overflow in TRUNC or ROUND. 
53 	MOD with negative divisor. 

Diagnostic messages occuring during binding have the following distinctive form: an indicator line describing the error, followed by one or more program text tines describing where the error occurred. The following indicator lines can occur:

*UNDEF*	identifier
*DUP*	identifier
*UNDECL*	label
*DUP*	label
*TYPE*	identifier

The indicator lines *DUP* identifier and *UNDEF* identifier are each followed by one text unit which contains the cited identifier occurrence.

The *DUP* diagnostic is generated at a defining occurrence of an identifier if the identifier has a prior defining occurrence at the same block level.

The *UNDEF* diagnostic is generated at a referring occurrence of an identifier if the identifier has no prior defining occurrence at the same or at any higher block level which would be visible to this referring occurrence.

The indicator line *TYPE* identifier can indicate an inconsistency between the types of the upper and lower bounds of a subrange type; it can also be generated by a STRING type with a noninteger length. The identifier in the indicator line is a type identifier appearing in either the subrange or string type; this identifier refers to a type which is inconsistent with the definition in which it occurs. This definition occurs in the text unit following the indicator line.