Memmgr; Command String Interpretation - ZiLOG Z80-RIO Operating System User's Manual

2.3.1 MEMMGR
Subroutine calls to the system entry point MEMMGR can be
used to allocate, deallocate, or determine the status of
designated memory areas. Appendix I gives the details of
these subroutine calls. Alternately, memory segments
may be allocated, deallocated, or the current memory
map displayed from the command level. Refer to Chapter 5
for details of the ALLOCATE, DEALLOCATE, and DISPLAY
commands.
2.4 COMMAND STRING INTERPRETATION
Whenever RIO is ready to accept command input, the prompt
character '%' is printed on the console output device. All
characters entered (up to a maximum of 256, subject to
device driver editing, see section 3.4.3) after the prompt
character, up to and including the first ASCII carriage
return (CR), are entered into the command string buffer.
This input constitutes the command input string. The
command separation character
I:'
is used to terminate a
command but does not terminate command input. Thus, as
many commands may be entered at one time as can be
contained in the 256 byte command string buffer.
Several characters have special significance to the command
string interpreter. As noted above, carriage return and
semicolon are used to terminate commands and are
therefore referred to as terminators. Space, horizontal
tab (ASCII 09H), and left and right parentheses can sep-
arate command names from optional parameter lists and
are referred to as delimiters.
There are two modes of providing system information to the
user. In verbose mode, each command is echoed as it is
extracted from the command string buffer. This is useful
to verify input or when entering multiple commands per
command string. In brief mode, commands are not echoed
(except as entered).
After a command has been located in the command input
string, an attempt is made to match it against a list of
internal commands. In doing so, an internal command name
may be abbreviated to the extent to which it is
differentiable from other internal commands. For example,
- 13 -