Imperial College, University of London
GR-145 62 Kifissia
Compile and run. Give the following lines as input:
OLD LANDER.BAS RUN
Be sure not to run out of fuel!
This is the DDS-BASIC Interpreter (Version 1.00).
RUN LIST NEW OLD filename BYE SAVE filename
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
|Line length||999 characters|
|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.
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.