HP 3000 Manuals HP 3000 Manuals
Using Magnetic Tapes
Magnetic tapes can be directly read or written from FORTRAN 77 programs
by a FILE equation. As a MIL-SPEC 1753 extension to the ANSI standard,
such tapes can be read or written in multiple logical files on the same
tape. The most portable format is a fixed record length ASCII file with
a specified blocking factor of one. However, the blocking factor of one
wastes tape because the interrecord gaps are longer on the tape than on a
single formatted record of normal length. For example, the equation
:FILE OUTFILE; DEV=TAPE; REC=-80,10,F,ASCII
with the FORTRAN 77 statements
OPEN(16,FILE='OUTFILE')
DO i = 1,400
WRITE(16,*) " This will be written on a tape 400 times."
ENDDO
causes a tape file to be created with ASCII logical records 80 bytes long
in blocks of 10 logical records per physical record.
FORTRAN/3000 programs that use the UNITCONTROL intrinsic are supported by
HP FORTRAN 77/iX. All the options of the FORTRAN/3000 version are
supported on HP FORTRAN 77/iX, including those operations commonly used
for magnetic tape handling.