Table of Contents
Advertisement
Section A:
System interface
A.9. EOS Flags
EOS maintains a flag byte in its system variables area.
It is described
in
chapter
A. 8
under the name
11
EOSFLAG
11
with an offset into the
system
variale
1
area of 57H.
This flag byte holds a number of user - alterable
flags
which
control
the overall behavior of EOS.
The flags
are
not
affected by system restarts. Their meanings are:
Bit 7
Bit
6
Bit 5
Bit 4
Bit
3
- reserved to maintain CP/M plus compatibility -
reserved to maintain CP/M plus compatibility -
If this bit is set,
the Line Editor is activated. Upon a
call
of
EOS function 10 to read an input line from
the
console,
this line will be read using the screen
editor
of the computer system.
Normally,
this kind of input is
performed by the Mini editor of EOS.
If
this
bit is set,
a break character keyed in at
the
console
will
not
automatically
abort
the
program.
Instead,
the break condition is displayed at the
screen
and the operator is requested to respond.
This
bit
has been introduced to provide for
a
general
break
facility.
If
it is set,
EOS
checks
for
break
characters
on
each call.
If a break character has been
recognized,
the address of the corresponding system call
1s
diplayed
in conjunction with a
break
message.
The
Operator is offered various options for responding.
It
shall not be kept secret that there are certain
dis-
advantages
with this facility.
System
throughput
goes
down,
11
typing ahead
11
is no longer possible and some pro-
grams
processing break characters as normal input
won't
work properly.
In general, this feature is more a debug-
ging aid.
The remaining three bits are reserved for internal use. Bits
6
and
7
may
be
freely
used by application programs,
but if done so,
they are
no
longer compatible to CP/M.
For such purposes, it is recommended to make
use of the dedicated User flags within the system variables' area.
EOS system manual
Daeumling & Zimmermann
Page 23
Advertisement
Chapters
Table of Contents
