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Path: utzoo!attcan!uunet!seas.gwu.edu!mfeldman
From: mfeldman@seas.gwu.edu (Michael Feldman)
Newsgroups: comp.lang.ada
Subject: Re: Keyboard input
Message-ID: <2172@sparko.gwu.edu>
Date: 24 Sep 90 13:58:09 GMT
References: <39@screamer.csee.usf.edu> <920031@hpclapd.HP.COM> <2166@sparko.gwu.edu> <3808@goanna.cs.rmit.oz.au>
Reply-To: mfeldman@seas.gwu.edu ()
Organization: The George Washington University, Washington D.C.
List-Id: <comp.lang.ada>

In article <3808@goanna.cs.rmit.oz.au> ok@goanna.cs.rmit.oz.au (Richard A. O'Keefe) writes:
>[about single-keystroke input]
>
>I would like to know how such a package could be implemented under CMS
>or TSO.  (Any "power of 2" fan know what CANDE will let you do these days?)
>IBM's operating systems really don't believe in character transput to
>terminals.  Perhaps IBM _ought_ to be ignored, but _could_ it have been?
>
My impression (from only limited experience with CMS) is that single-character
I/O is difficult at best under CMS because the CMS device drivers (or "access
methods" in IBM parlance) assume non-scrolling terminals and line-oriented
input (hence the MORE...) message at the bottom of every screen. This is not
an Ada problem, rather an OS one. In fact, I tried using an _ASCII_ terminal
driver (provided, I think, for interactive APL users among others). Using
Text_IO to send escape sequences to the terminal, so that I could control
my own _output_ formatting, failed: the driver was willing to give up on the
MORE... dialog, but it mapped my nonprintable ASCII characters to blanks,
so the terminal-control sequences were ignored. 

I conjecture that a sufficiently adept assembler programmer could figure out
how to end-run the CMS device drivers and then write an interface package
to make it Ada-callable, but I don't think it would be easy. 

Given the differences between ASCII and EBCDIC character sets, I find it
amazing that a decent Ada could have been implemented at all on IBM mainframe
iron. There are in fact at least two quite decent systems out there, one
sold by Alsys, the other by IBM, supported, I believe, out of Toronto.

I take it you are using the IBM Ada "program product" for Ada on CMS. If so,
the system is really a TeleSoft product (I am not revealing any secrets here).
Anyone at TeleSoft know whether this sort of thing has been done?
---------------------------------------------------------------------------
Prof. Michael Feldman
Department of Electrical Engineering and Computer Science
The George Washington University
Washington, DC 20052
202-994-5253
mfeldman@seas.gwu.edu
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