Task

 verify the version/revision of your currently running (compiler/interpreter/byte-compiler/runtime environment/whatever your language uses) and exit if it is too old.
 check whether the variable "bloop" exists and whether the math-function "abs()" is available and if yes compute abs(bloop).


Extra credit

 Report the number of integer variables in global scope, and their sum.


10 LET totram=PEEK 23732 + 256 * PEEK 23733: REM Check that we have a 48k machine
20 IF totram < 65535 THEN PRINT "Your 16k Spectrum is too old": STOP
30 REM variables must exist before they are used, otherwise we get an error
40 REM we can poke a new error handler and check for variable not found.
50 REM I haven't implemented this, because I have forgotten the handler address
60 LET bloob = -4: REM make sure bloob exists, by creating it.
70 PRINT ABS(bloob): REM function will be present, ZX Spectrum Basic is standardized.