g77. Unformatted READ

[Chuck Lawson]

I am maintaining a suite of Fortran engeneering analysis codes, some of 
which date back to about 1970.  My problem is with a program that has a 
main program and about 12 subroutines.  This program compiles and links 
and executes ok using g77 under Cygwin, which in turn is under MS Win 
XP, but it fails on an unformatted READ when compiled and linked and 
executed using g77 under Redhat Linux 7.2.  This is all on the same 
Polywell PC, which has Win XP and Redhat Linux dual booted. The error 
message says unformatted io not allowed.  I have tried many 
rearrangements of the code, with and without an OPEN statement, but 
nothing works under Linux short of reducing the code to just the READ 
statement -- then it works.

Note that the error msg does not say something like unexpected end of 
file, or file not found, which would lead me to the source of the error. 
 What conditions can cause the message: "unformatted io not allowed" ?