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# FIX: EOF and BACKSPACE Cause GP Fault When the Unit Isn't Open

Article ID: 106729

Article Last Modified on 10/17/2003

APPLIES TO

- Microsoft FORTRAN PowerStation 1.0 Standard Edition
- Microsoft Fortran PowerStation 1.0a for MS-DOS
- Microsoft FORTRAN PowerStation 32

This article was previously published under Q106729

## SYMPTOMS

Passing an unopened unit number to the EOF intrinsic function or the BACKSPACE command generates the run-time error:

### FORTRAN PowerStation for MS-DOS

DOSXMSF : fatal error DX1020: unhandled exception: General protection fault;

### FORTRAN PowerStation 32 for Windows NT

Application Error
The instruction at "0x0001316e" referenced memory at 0x00000000". The memory could not be "read".

## CAUSE

The following run-time error should be produced:
run-time error F6420: EOF()
- unknown unit number

## RESOLUTION

Only use the EOF function and BACKSPACE command on units that are currently open.

## STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. This problem was fixed in FORTRAN PowerStation, version 4.0.

## MORE INFORMATION

The following sample code generates a DX1020 error (GPF) when run:

### Sample Code

    C Compile options: None
          logical l
          open(2,file='test.out')
          l = EOF(1)
          end

Additional query words: 1.00 4.0 gpf gp-fault

Keywords: kbbug kbfix KB106729