Applies To:
  • CitectSCADA 1.00, 1.01, 1.10, 1.11, 1.20, 2.00, 2.01

Question: Sometimes I can't start any more applications. Windows displays the error 'no enough memory to start application', but the Program Manager About box says that there is plenty of memory and system resources. 

There are two main reasons why this happens. The first situation happens infrequently , and is related to the available free system resources. When called on to load a program, Windows checks to see if there's at least ten percent system resources free. If not, it stops the load sequence. The second cause is much more common, and involves available memory below 1MB. When Windows creates a new task, it needs a small amount of memory (512 bytes) below 1MB. If it cannot get this memory, the load will fail. Windows will display the 'not enough memory to start application' error. This limitation is as a result of the design of Windows, and occurs because Windows still has some connections back to the old DOS 640k limit.

You can help Windows load more programs by freeing as much memory below 1MB as possible. You should load DOS high as well as any drivers, TSR's, etc.

See also Q1407