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Blog | CBT Tape

Open Mainframe Project Announces CBT Tape Update 505

By | June 5, 2023

Written by Sam Golob, leader and manager of CBT Tape




The “CBT Tape” collection of free software is generally updated “version-wise” about twice a year.  This does not mean that you can’t get to updates that came in-between times.  Those updates can be found on our website. Twice a year, these updates are MERGED into the main collection and a new version of the collection comes out.

It wasn’t always this way. We didn’t always have a website. The collection was actually maintained on a “real tape volume” for a long time.  Then, since the contents of the collection had to always remain on tape, there was no other way to show the updated files, than to make a new tape version more often.  When the tape was maintained that way (on actual tape), more than 15 versions per year had to be made.

In Arnie Casinghino’s 15 years of making tapes for this collection, from 1975 to 1990, Arnie took the tapes through 320 tape versions.  You can figure out that this amounts to more than 20 new versions per year.  When I took the collection over, I had to do about the same thing for a good while, until 2003, at CBT Tape Version 463.  Then I started making fewer version updates, relying on the Updates page of the CBT Tape website, for people to use and obtain the updated and new files.


Most CBT Tape files consist of a PDS, or partitioned dataset, which you can picture as a subdirectory.  A partitioned dataset contains one, or many “members”, each of which is a data file or a program.  In order to load a partitioned dataset onto a single tape file, it has to be “sequentialized”, or in other words it has to be converted into a single individual file, before it is copied to tape.  This process is done by the use of several programs that come with the collection, and which are used for this purpose.

Some single CBT Tape files contain several hundred programs.  With more than 1000 files in the CBT main collection, and more than 300 files in the CBT Overflow collection, the entire collection contains thousands of tools for systems programmers to use.


In May of 2023, we merged more than 80 updated CBT Tape files into the main collection, to produce CBT Tape Version 505.  Many of these updated files were produced on the Linux Foundation’s z/OS machine, which they have kindly provided for the use of CBT Tape maintenance and development.  Many of the contributors to the newly updated collection are retired systems programmers, and the Linux Foundation’s z15 computer, running the latest z/OS version, provides them with a place to work, and to re-hone their skills. These 80-or-so files were all supplied over a period of about half a year.

Although the collection is quite enormous, we make a considerable effort to keep it up-to-date.  At the same time, we do not usually get rid of the older versions of programs, because quite a few shops are still running back-level systems.  We try to accommodate everybody.  We make an effort to help all of our “users”, and try to make sure that they are satisfied.

We do keep an archive of older versions of the CBT Tape collection so that any program versions that are older, may still be found, and they can be made available to those people who might still need them.

So in short, keeping up the CBT Tape collection is an ongoing job, and we try our best to help make the work of systems programmers around the world easier.  AND, all of this stuff is FREE. 

Learn more at or watch the video below.