Richard Heathfield wrote:
As I've said before, I do consider CMS, CP/M and early MS-DOS -- and
RT-11 -- to have single, fixed directories. OS/360 et seq is more
problematic; it does (at least did) have catalogs which provide the
function of directories and even directory trees, but aren't organized
into separate directories the way we are now used to.
Yeah, the PDP-11 I used with an RT-11 OS had no subdirectories.
All the files were in one place, had to be unique names and limited
to 8 characters (I think). It was a real PITA.
6.3, and drawn from the same 'RAD50' character set used for
object-file symbols: 26 letters -- uppercase only, although most
programs and certainly the 'standard' command parser allowed you to
enter lowercase and upshifted it for you; 10 digits; dollarsign;
underscore; period, which you couldn't actually use in a filename*
because it was the separator; and space (trailing only). (* I don't
recall testing if you could put period in the extension, where the
parse would be unambiguous, and no longer have the opportunity.)
And just to be clear, all the _directory entries_ were in one place,
in the (one-per-volume) directory. The file contents were of course in
different places, in general spread over the volume.
AIR there was a DECUS driver, I think later added to the official
system, which could 'mount' a (single large) file on a (real) disk as
a virtual disk volume, and thus have a (single) directory and files
within that. That provided the effect of nesting, but clumsily, and
without allowing practical recursion/treewalking. (The same, pretty
obvious, concept has been invented in many other places as well.)
- David.Thompson1 at worldnet.att.net
