ZiLOG Z80-RIO Operating System User's Manual page 88

DO DO
of whether or not they are used in that expansion.
After command string editing according to the above rules,
a system call is generated to execute the resultant command
string.
This command is reentrant (and has the 'force allocation'
property) and may call itself up to a depth limited only by
the amount of memory available. That is to say, FILE.X may
contain the command 'DO FILE.Y', which may contain the
command 'DO FILE.Z', etc., down to a level where insufficient
memory exists to allocate buffer space. For short command
files (a few records) in a 32K system, this depth is
approximately 15, depending on memory requirements for
other command executions.
***
WARNING
***
Due to the force allocation property of this command, it
will over-write the memory where it is loaded, whether or
not the memory is all ready allocated. This command should
be linked to load at an address that will not affect memory
that is preallocated for system use.
I/O UN~T UTILIZATION
Unit 0: command file
Unit 2: error messages
EXAMPLES
The examples have the fOllowing format:
FILENAME:
Command:
Result:
DO file contents
Command line entered
The expanded file contents which
are to be executed.
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