Asynchronous Serial Communications Programmer's Reference Manual (32022-90052)

298 AppendixA
Comparing MPE/iX Systems to MPE V Systems
Software Characteristics
NOTE When a device is closed (using the FCLOSE intrinsic) on an MPE V
computer, the initial default parity setting is restored. On MPE/iX
computers, parity is not restored at FCLOSE. This means that to
change parity using the FCONTROL intrinsic, the default parity in the
application must be restored before closing the device.
Read Timer
On MPE V computers, the read timer must be enabled (FCONTROL20)
before every read whose duration you wish to measure. With MPE/iX
computers, the timer is always enabled and measures every read. This
means the following:
• There is no need to use the FCONTROL20 intrinsic. The timer is
automatically enabled.
• The read timer’s value should be obtained before any other reads
occur. Otherwise, the value of the read timer will be for the most
recent read, not the read that originally needed to be timed.
• FCONTROL21 cannot be used to disable the timer. (Calling this
intrinsic has no effect on the timer.)
Additional End-of-Record Characters
With MPE/iX, the characters listed in Table A-6 should not be used as
additional end-of-record characters. An error message will not be
received if one of the characters in the table is entered as an additional
EOR, but the character will not terminate a read when it is entered.
With MPE V, any character can be used as an additional end-of-record
character, except for the list in Table A-7.
Table A-6 Unrecognized AEOR Characters (MPE/iX)
On MPE/iX computers, only one AEOR character can be designated for
a device at any given time with FCONTROL(25), and multiple AEORs
can be designated with FDEVICECONTROL(192,40).
ASCII Character Terminal Keys Octal Code Hex Code
NUL(Null) [CTRL]-@ % 0 $ 0
DC1(XON) [CTRL]-Q % 21 $11
DC3(XOFF) [CTRL]-S % 23 $13
Current Subsystem Break
[CTRL]-Y (by default)
a
a. In transparent mode, define the subsystem break character through the
FCONTROL41 intrinsic
% 31 $19
DEL(Rubout) [DEL] % 177 $7F