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CHAIN COMMAND
6.4 -- Execution Operators
the
printer.
Execution
~ould
not
resume until aTter the
operator had depressed any keQ on the system console.
0.4.3 Error status word
Among the operating system's
resident
variables
is
a
two-byte
error
status
~ord.
Each MOOS command
~ill
set or
clear a bit within this status word to indicate the status
o~
the
command's
comp letion.
The
error
status Ulord has the
TolloUling Format:
F E D
C
B
A
9 8 7
6
5 4 3
2 1 0
Error
Error
I
----
Error Type
Bits 0-7 describe
error
Error Mas k Flag
Bit B (S-A unused)
Error
Status
Fla~
Bit F (C-E unused)
Normallql
a~ter
the completion of each command, all
bits
of
the
Error
Status and the Error Type
are
cleared
(=
0).
The
Error Mask is not affected by MDOS
commands.
If
an
error
occurred
during
the
commandl the Error Status Flag (bit F)
tali 11 b
e set
b
y
the comma
n d .
In
add i
t
i
on, an
E r
l' 0
r T
y
P e
UI
i
11
be
set
into
the
lower
hal~
o~
the status word (bits
0-7).
The Error Type is used to indicate which error
was
detected
by
the command.
UsuallYI
the CHAIN process will
abo~t
anytime the
Er~or
Status Flag is set by one of the commands
invoked
from
the
intermediate
~ile.
The
Er~or
Mask can be used to inhibit
CHAIN process
abo~ting
due to command
er~ors
by
setting
the
Error Mask Flag (bit B) to a 1.
The
Execution
Ope~ators
can affect certain
pa~ts
of the
status word.
The following symbols are used to refer to
the
various parts of the status
wo~d:
I
,,/
)
'-../
Page
06-10
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