Date : Tue, 29 Mar 1983 11:18:24-PST
From : Lauren Weinstein <firstname.lastname@example.org>
Subject: ITS binary format
I've had lots of problems with "com" binary files on ITS over the years,
and not just from Unix systems -- so don't blame Unix! The issue is that
ITS stores these files in a sort of "packed" format that is oriented
around its 36 bit words, and includes some other header information
as well. For example, let's say you have a file that you uploaded
to ITS using the LMODEM "com file" mode. Now you try to FTP the file
from ITS to a non-ITS system (in binary/image mode). The file you get
has this packing and strange header information included. Small wonder
that squeezed files won't unsqueeze! When instead you download such a file
through LMODEM, ITS performs the conversions and you get a "proper"
binary file again.
Ideally, ITS should have a special FTP mode which would convert
the ITS com file format back to "real" binary on the fly during
transfer. I suspect that the ITS folks never considered FTP'ing
of com binaries to non-ITS systems to be a "high-demand" type project.