Best Language Tool: Diomidis Spinellis 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: - Line editor using line re-entry. - A line number with nothing following it, deletes the line. Input format: - Free format positioning of tokens on the line. - No space is allowed before the line number. - Exactly one space is needed between the OLD or SAVE command and the filename. - ALL INPUT MUST BE UPPERCASE. 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 (c) 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.