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

Appendix A 301
Comparing MPE/iX Systems to MPE V Systems
Software Characteristics
the FDEVICECONTROL intrinsic, you can choose to either remove the
character from input and back the cursor up one space, or to remove the
character from input and erase it (backspace, space, backspace).
Special Response to a Linefeed Character
The MPE V ATP/ADCC software will react to a linefeed (LF) character
by echoing a carriage return and linefeed, then stripping the linefeed
from input data. The ASC software will not do this and will not strip
linefeeds from input data. This is different during line block mode only.
Special Output for a Formfeed Character
For some devices, the MPE V ATP/ADCC software will substitute the
linefeed (LF) character for the formfeed (FF) character. On MPE/iX
computers, formfeed replacement is supported in carriage return, but
not in user data.
Critical Writes
With MPE V, all writes to asynchronous printers are critical writes.
This means that the file system reports the completion of the write to
the program initiating the write only after the data from the write has
been printed out. In other words, the write is complete only after the
write is successful. With MPE/iX, the completion of every write is
reported by the file system when the DTC sends the data to the printer.
Since this is before the data has actually printed, the completion of a
write does not guarantee that the write was successful.
Since the ASC software does not wait for each line to print before
continuing, data can be sent to printers more quickly.
Related Operating System Changes
The following functionality of the MPE V operating system is not
supported on the MPE/iX operating system, and has some significance
for the asynchronous subsystem.
MPE Commands
The :DATA and :COMMAND commands, sometimes used to log on to
terminals, are not supported on MPE/iX. The :JOB command, while
still useful to stream jobs, cannot be used to log onto a terminal.
File System Intrinsics
The FCARD and PTAPE intrinsics, sometimes used with asynchronous
devices, are not supported on MPE/iX.