QBasic ran out of room in memory for data, variables, and
some other information. Try modifying your data space
requirements as follows:
  -  Use a smaller file buffer in the OPEN statement's
     LEN clause.
  -  Use the $DYNAMIC metacommand to create dynamic
     arrays. Dynamic array data can usually be much
     larger than static array data.
  -  Use fixed-length string arrays instead of
     variable-length string arrays.
  -  Use the smallest data type that accomplishes
     your task. Use integers whenever possible.
  -  Use CLEAR to modify the size of the stack.
  -  Do not use source lines longer than 256 characters.
     Such lines require allocation of additional
     text buffer space.