Re: Ada replacements for DOS I/O

[<cwarwick@fox.nstn.ns.ca>]

On 27 Oct 1994 19:04:50 -0400, 
Robert Dewar  <dewar@cs.nyu.edu> wrote:

>The failure to do concurrent I/O is certainly not a bug (nothing in the
>Ada standard requires, or even implies, that I/O done from one task is
>concurrent with the execution of other tasks).

No, but it does require a higher priority task take precedence over a 
lower. With the Alsys DOS product all task processing regardless of 
priority ceases. I think the nature of Ada tasking is such that I/O be at 
least interruptable when a higher priority task becomes ready to run.

>If you need concurrent I/O, put an operating system on your PC (many
>choices including OS/2, NT, Solaris, SCO Unix, Linux, BSD386, Lynx,
>Nextstep), and then shop for a compiler that definitely supports the
>concurrency that you need.

The most logical step is of course to write the IO functions we need in 
Ada (or find someone who already has, hence the start of this thread) and 
then the bug goes away, regardless of operating system...

>You burned yourself on this one by making a totally unwarranted assumption!

I don't think its unwarrwanted. Alsys provided use with all the OS tools we 
needed to implement this project, which included interrupt handling, 
multiple tasking, and IO to nonstandard cards. I don't think given all this 
it was unreasonable to assume they had thought about the interaction 
between tasks and DOS.
 --
 Lorne Elliot in a Conan the Barabarian suit, or
 "Beware the fool, for only the fool may speak the truth"

 Chris Warwick
 cwarwick@fox.nstn.ns.ca
 warwick@anchor.hfx.prior.ca