Best Language Tool

Diomidis Spinellis
Imperial College, University of London
Myrsinis 1
GR-145 62 Kifissia
Greece

Judges' comments:

Compile and run. Give the following lines as input:

OLD LANDER.BAS
RUN

Be sure not to run out of fuel!

Selected notes from the author:

This is the DDS-BASIC Interpreter (Version 1.00).

Immediate commands:

RUN LIST    NEW OLD filename  
BYE SAVE filename

Program commands:

variable names a to z       variables initialized to 0 on RUN
FOR var = exp TO exp        NEXT variable
GOSUB exp           RETURN
GOTO exp            IF exp THEN exp
INPUT variable          PRINT string
PRINT exp           var = exp
REM any text            END

Expressions (ranked by precedence):

Bracketed expressions
number (leading 0 for octal, 0x for hex, else decimal), variable
Unary -
* / 
+ - 
= <> 
> < 
<= >=
(* and + are also used for boolean AND and boolean OR)
Boolean expressions evaluate to 0 for false and 1 for true

Editing:

Input format:

Limits:

Line numbers 1-10000
Line length 999 characters
FOR nesting 26
GOSUB 999 levels
Program Dynamically allocated
Expressions -32768 - 32767 for 16 bit machines,
-2147483648 - 2147483647 for 32 bit machines

Error checking / error reports:

No error checking is performed. The message ‘core dumped’ signifies a syntax or semantic error.

Hosting Environment:

ANSI C, traditional K&R C or OSF ANDF
ASCII or EBCIDIC character set
48K bytes memory

The Speed of DDS-BASIC Interpreter (Version 1.00). relative to Microsoft Advanced BASIC 3.31 is Approximately 60%.

The code size could be further reduced by doing ugly things like not declaring the return type of functions, not freeing memory, #defining define, and joining lines. In its present 1536 character form the program is reasonably portable (it may fail to run in a tagged object architecture) and nicely formatted (it fits in an 80*25 screen).

Copyright © 1990, Landon Curt Noll & Larry Bassel. All Rights Reserved. Permission for personal, educational or non-profit use is granted provided this this copyright and notice are included in its entirety and remains unaltered. All other uses must receive prior permission in writing from both Landon Curt Noll and Larry Bassel.