synchronous v. asynchronous I/O

[jmoody@DCA-EMS.ARPA (Jim Moody, DCA C342)]

Mike Feldman (MFELDMAN@GWUVM.bitnet) writes "I have the fairly clear
impression that TEXT_IO wasn't really intended to be used inin a tasking
environment."  I don't see why TEXT_IO is any different from any other
I/O package in a tasking environment.  Any tasking rpogram which accesses
a file from two (or more) tasks has to be careful.  Section 9.11 applies.
Implemetations which block all tasks when one does I/O to standard_input
or standard_output are "protecting" programmers from the ill-effects of
writing erroneous programs, because a whole bunch of people wrote erroneous
programs (the example Mike gives is one task doing PUT("ABC") and another
doing PUT("DEF") with the screen result ADBECF) and complained when the 
implemenation did the unexpected.  Section 9.11 says that if one task 
updates a shared variable, another should not without explicitly synchron-
izing with the first.  standard_output is a shared variable.

It seems clear to me that part of the pijt of allowing tasking in a single
processor environment is to continue computing while the guy at the
terminal is scratching his head.  This mandates context switching at I/O
points.  I hope that there is no AdaBoard policy which opposes this view.

Jim.