125. DIM oddity
     ~~~~~~~~~~
If you have already dimensioned a numeric or string array in a program, such
as A$(100), FRED(55) or mem%(300), then any attempt to redimension it will
result in the error message "Bad DIM". In some versions of BASIC, though
sadly not BBC BASIC, you can legally redimension an array, or reclaim the
memory it occupies, provided you 'kill' it first, eg KILL A$ , ERASE A$ etc,
(the syntax varies).

However, if you dimension an area of memory with the syntax DIM mem% 100 , as
one might do if reserving memory for some data or machine code, then it can
be redimensioned without killing it first, and without generating any error
message. If this sounds too good to be true, then you're dead right!

Every time you redimension the area, even if you are reserving the same or
less space than before, the old area is 'thrown away', and new space
reserved. If you don't do this too often, then it may be useful to you, but
try the short program below and see how it rapidly gobbles up all the memory.
This applies equally to all versions of BBC BASIC that I have come across.

 10 REPEAT:DIM A% 50:UNTIL FALSE
 20 END