On Sun, Apr 22, 2018 at 1:01 PM, Lars Brinkhoff <lars@nocrew.org> wrote:

Dan Cross wrote:
> Why was it called drum? I imagine that's historical license coupled
> with grad student imagination, but I'm curious if it has origin in
> actual hardware used at UC Berkeley. Clem, that was roughly your era,
> was it not?

Seems like the Project Genie 940 at UCB had a drum. Maybe someone
wanted to carry the tradition forward.

The 'someone' in all of this was Bill Joy (wnj). As I said, in those days, all of us knew of older systems that used 'paging drums' - it was pretty common term for the hunk-a-storage that the system dedicated to be available to page itself. it really is just like the fact that by the time of the VAX, DEC was not shipping core memories at all (and few 11's shipped with core either as the thanks to Moore's law, the price of semiconductor memory had dropped), so calling the main system memory 'core' was obsolete. Thus, the UNIX term 'core dump' was really meaningless. [In fact, Magic, the OS for the Tektronix Magnolia Machine has 'mos dump' files - because I did that].

But the term 'core file' stuck, tools knew about, as did the programmers. The difference is that todays systems from Windows to UNIX flavors stopped needed a dedicated swapping or paging space and instead was taught to just use empty FS blocks. So today's hacker has grown up without really knowing what /dev/swap or /dev/drum was all about -- in fact that was exactly the question that started this thread.

On the other hand, we still 'dump core' and use the core files for debugging. So, while the term 'drum' lost its meaning, 'core file' - might be considered 'quaint' by todays hacker, it still has meaning.

Clem