Purging a Directory. You can purge an
directory just as you
would a variable: switch to the directory that contains the directory to
be purged, put the directory's name on the stack, and execute
If the directory to be purged contains variables or subdirectories, you
must purge the variables or subdirectories before you can purge the
directory. Here's a general procedure.
1. Switch to the directory to be purged.
2. Execute CLUSR to clear the directory.
3. Switch to the parent directory.
4. Purge the directory.
n - E
error occurs in step 2, the directory
contains a subdirectory that isn't empty. In this case you must per-
form steps 1, 2, and 3 to clear the subdirectory. You can then
continue with step 2 through 4 to purge the directory.
Moving Up and Down the Directory Structure. Chapter 28 in-
cludes programs for moving up the directory structure (switching to a
parent directory) or moving down (switching to a subdirectory). See
"Changing Directories" on page 275.
The HP-28S automatically saves copies of command lines, arguments,
and the stack. These copies enable you to recover from a mistake-to
go back to where you were before the mistake. You can then redo a
calculation without starting over from the beginning. The copies of
command lines and arguments are also handy for repeating
These copies can consume a significant amount of memory. For each
of these recovery features-command lines, the stack, and argu-
ments-you can choose whether to enable or disable the feature. The
operations to enable or disable the recovery features appear in the