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Section C:
Utility Programs
****************
•
$SAVE
•
****************
C.l7. $SAVE- Dump Memory to Disk
This
program
has a very specific function ordinary users
will
hardly
ever need. It is of interest for programmers only.
Under CP/M 2.2 resp. DiCOS, the SAVE command was firmly installed in the
command interpreter.
By that means it was possible to transfer parts of
the
memory
contents to a disk file.
It is usual practice
to
load
a
program into memory using
a
suitable test program ("debugger"), test and
alter the program and with the session finished,
to save the program to
disk by means of the SAVE command.
EOS does not know this command,
as the command interpreter is a program
like
any other program,
thus residing in the same area of memory.
For
this
reason,
another
mechanism had to be implemented to
provide
for
saving
memory
contents
to disk before memory is
overwritten
by
the
command interpreter.
Essentially,
$SAVE is nothing else but a function module.
If you enter
the command
$SAVE
the
module is loaded into memory directly beneath the EOS system entry,
where it remains inactive until the next program terminates.
After
the
succeeding program has finished (e.g.,
a debugger), $SAVE comes in with
the message
EOS V3 - Memory save utility
File name
Here
you would enter the name of the file to which memory contents
are
to
be transferred.
If you just press "ENTER" and nothing
else,
$SAVE
aborts. If the file specified is already present, you are inquired:
filename.typ: Erase? (Y/N)
If at this moment,
you type anything else but
"Y",
another filename is
asked for.
The next questions concern the start and end address of
the
memory area. After the
fi~e
is written, $SAVE disactivates itself.
EOS User's manual
Daeumling & Zimmermann
Page 93
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