Turbo Pascal strings have a length byte in front. Since a byte has the range 0 .. 255, this limits a string to 255 characters. However, the Pascal string schema, as defined in section 18.104.22.168.3 of the ISO 10206 Extended Pascal standard, is a schema record:
type String (Capacity: Integer) = record Length: 0 .. Capacity; String: packed array [1 .. Capacity + 1] of Char end;
The + 1 is a GPC extension to make it feasible to automatically add the #0 terminator when passing or assigning them to CStrings. Thus at the expense of a little added complexity (must declare capacity, don't use GetMem without explicit initialization of the Capacity field, and the additional space requirement) you can now have very long strings.