Tree by Rick Andrews

Have you ever lost a file on your Series 3 - or rather, forgotten
where you put it? Or wonder why the internal drive is using 30K
more than usual, only to find two copies of your phone list lying
around. (Remember that sorted one you put into \MISC last week?) It
can be a bit of a pain having to play hide-and-seek using the
system directory (psion-*) command, even more so with the early
versions of the OS that don't have it! So I wrote this little
utility to help. Here is an example of its output :-

A:\
ÃÄDAT\
³ ÃÄPHONE.DBF
³ ÀÄMISC\
³   ÃÄTX.DBF
³   ÀÄWLIST.DBF
ÃÄAPP\
³ ÃÄZLOTY.OPA
³ ÃÄUTILS.OPA
³ ÀÄSUSHI2.OPA
ÃÄWRD\
³ ÀÄMISC\
³   ÀÄQUOTA.WRD
ÀÄOPL\
7 files

Could be useful, couldn't it? Fair enough, it doesn't show dates or
sizes, but it is a start. You can see which files are where, how many
sub-directories you have and get a picture of the layout of your
disk. (Think you've seen this utility before? Its based on one from
MS-DOS, but that one doesn't show filenames.)

Okay then, how does it work?

It starts by asking which disk is to be examined, then scans that
disk using the OPL command DIR$ which gives the names of the files
and sub-directories belonging to a directory. i.e. the entries in the
file system.  An entries depth (how far down the tree it is) can be
determined by keeping a count of how many sub-directories have been
used to reach it. Both these bits of information are stored in
arrays; called gaName and gaDepth. (I use the 'g' to remind me that
the variable is global, and the 'a' for array.) The scanning a bit
time-consuming (about .5 second per entry) so the name of the
directory being scanned is "BUSYed" onto the screen, to let you see
what is happening.

The scanning is done recursively - that is, the procedure Descend:
calls itself. This is one way of ensuring that the entire tree is
checked, and also allows the array of entries to be built up in a
logical order, i.e. the directory, its children, and then its peers.

Having completely scanned the disk, the arrays are used to work out
the shape of the tree (ShowTree:), by comparing the relative depths
of entries.

This utility could be done with no arrays, which would reduce the
amount of memory required at run time, but this method would involve
repeated calls to DIR$ to find the entry depth, making it very slow.

Well, thats it! I'm going to get some sleep. Good night!

P.S. By the way, the ROM:: drive I mentioned last time cannot be seen
using the system directory command (psion-*). Try using Open File in
World (for example) to see the names (like Agenda.App). Don't forget
the Control-Tab, Control-Enter business to select the ROM:: drive.
Then you can use a one-liner in OPL like COPY "ROM::AGENDA.APP", "M:"
to copy it to the internal RAM drive where it is more accessible. Or
you can look at it with a file viewer like HexDump. (I'll send an
article about HexDump next time.)