Copy data from DOS to heap.
Source position: go32.pp line 180
| procedure copyfromdos( | 
| var addr; | 
| len: LongInt | 
| ); | 
Copies data from the pre-allocated dos memory transfer buffer to the heap.
Parameters:
Notes: Can only be used in conjunction with the dos memory transfer buffer.
Check the int31error variable.
| 
 | Return DOS transfer memory buffer size. | |
| 
 | Return offset of DOS transfer buffer. | |
| 
 | Copy data from heap to DOS memory. |