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~ENERAL
SYSTEM OPERATION
2.5 -- System Console
CARRIAGE RETURN
will
automatically
perform
both
car~iage
return and line reed functions.
2.5.2 Breal< key
The
BREAK
key
is
used as a
controlled-abo~t
function
key.
Most MDOS commands that take a long
time
to
complete
their function periodically check to see if the
BREAK
key
has
been depressed.
If it
has,
the
command
will
come
to
a
premature,
but controlled, termination point.
Th e
BRE.AK
key
shou
let
be used,
whenever pass i
b
le,
as an
alternative
to
using
the
EXORciser's
ABORT
or
RESTART
pushbuttons.
The controlled abort that is achieved with the
BREAK
key ensures that all system tables are
ln~act.
~lnce
termination
is
dela~ed
until all critical diskette accesses
have been completed, no file space is lost nor is any
sqstem
table
destroyed.
Such
precautions cannot be guaranteed if
the ABORT or RESTART pushbuttons are used,
since the operator
has
no way of knowing
~hether
or not diskette data
t~ansfers
are in progress.
2. 5. 3 Cont1"ol-W
Cont,..ol-W i.s actually. a combination
'of
two
k"eys
being
depressed
simultaneously:
the CONTROL or CTL key and the W
key.
This
combination
is
used
to
halt
the
displaq
of
information
on
the system console or printer.
All commands
that respond to the
BREAK
key abort
function
will
also
be
IIhaltable
ll
IVlth
the
CTL-W
key.
Most
MDOS
commands that
display
more
than
a
fe~
lines
o~
information on
the
console
will
occasionally
check
to
see
if the CTL-W key has been
depressed.
I
r
a CTL-W is detected
I
the command
wi
11
susp end
processing
until
any
other
key on the console keyboard is
d e pre sse
d
(e x
c e p t
I
0
.p
C 0
u r s e , an
0
the r
C TL -W ) .
T his
f eat
U 1"
e
is
particularly
useful
to
hold the display for viewing on
systems that have
a
CRT.
In additionl
ir'
output
is
being
directed
to
the
p1"inter,
the CTL-W can be used to suspend
printing until the paper is realigned.
2. 5. 4 Control-X
Control-X is actually a combination of
two
keys
being
depressed
simultaneously:
the CONTROL or CTL key and the X
key.
This combination is used to cancel the input line
that
was Just entered by the operator (before a carriage return is
depressed),
All
system
input
from
the
console
supports
CTL-X.
Any
~haracters
ente1"ed on the
cu~rent
input
lin~
thus
rar will be
deleted
and
input
can
be
resumed
rrom
the
beginning
af
the line.
A
carriage return and line feed will
be sent to the consolel
so that the operator has
a
positive
Page
02-08
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