IBM CMS dumpfile idiocy

Dave Wade dave.g4ugm at
Wed Dec 16 14:11:44 CST 2015

> > CMS TAPE files are not intended to be used by other systems and the
> > format is undocumented (well except a little in the source code) and
> > has changed several times as disk formats have changed.
> I've been on the receiving end of this before--several times.  Damned
> inconsiderate programmers with no thoughts of the future.  

I think CMS TAPE dates back to 1972 or so. It also has two character years
so definitely no thoughts for the future...

> Undocumented
> format--how quaint.

The manual is pretty clear. Even in 1972 it said ..

"The TAPE COMMAND is used solely with CMS files; Therefore, the files are in
a unique format".

If you wanted to write portable tapes, you used MOVEFILE but most folks
didn't because MOVEFILE needed FILEDEF cards to define the block size and
record format.

> Right now, I'm puzzling over a QIC tape that was apparently made early on
> using Sytos, but the header doesn't match any version of Sytos that
> I've seen.   Wonderful.

At least the original VM/370 was open source freeware, so you could figure
out the format as you have the assembler source that writes it....
... and there are Program Logic manuals as well. 

Ah the joys of computing, wouldn't life be boring if everything worked...

> --Chuck

p.s. any luck in extracting the files?

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