Re: Ada Terminal Emulator evaluation notes

[Ross Higson <rossh@zip.com.au>]

Simon,

I'll answer this in the newsgroup as well since you raise some good 
points, but (for future adventurers,
who I hope won't be put off by Simon's experience !) direct email will 
normally get a faster response.

Simon Clubley wrote:

>Installation.
>-------------
>1) The clean rule is called by the makefile on a build; it causes the build to
>fail on the initial installation as the files to be deleted do not exist yet.
>I got the build to start by commenting out the calls to the clean rule.
>
I'll try to make my Makefiles more robust. Do you by any chance also 
have GTKAda installed ?
This can really mess up GNU Make. Not just my stuff - I also cannot 
build GWindows programs
with GTKAda installed. Do you think there might be some kind of 
conspiracy going on here ? :)

My solution is to temporarily rename the GTKAda directory to get it off 
my path when building any
non-GTKAda stuff. If I cannot make my makefiles work in such cases, I'll 
make an appropriate
note in the documentation. Thanks for reminding me about this one.

>Emulator.
>---------
>3) The DEC keyboard is not active. This applies to the keypad, the editing
>keys and cursor keys. The manual implies that there is an advanced menu, but
>I cannot find it. This has stopped me from running a large range of the
>tests that I would normally run and is a show stopper in a VMS environment.
>
You have to set the emulation mode (e.g. to vt100). Use the option 
"/mode" on the command line,
such as "comms /port=3 /xin /xout /mode=vt100" The emulation mode 
particularly affects the
keyboard, as described in Appendix A. The default emulation mode is PC, 
not VTxxx. The
advanced menu is enabled by the "/advanced" option. If you enable this, 
you can change the
emulation mode from within the program as well. For example, use the 
command
"comms /port=3 /xin /xout /mode=vt100 /advanced".

>4) Scrolling is very slow on a 233 Mhz machine; probably too slow to be usable.
>
Performance comments noted - improvements are in the pipeline, but 
compatibility issues get
higher priority at the moment. However, I'll update the documentation to 
recommend 500Mhz
(which is what I normally test with) as the minimum for acceptable 
performance.

>5) The results from a $ set term/inquire give occasional unusual results.
>See the following session:
>
>[snip]
>
>This page length of 7 is clearly wrong.
>
I'll investigate. Looks like I may be sending back the current cursor 
location instead of the screen size.
I'll have to hunt down which particular terminal report is being used here.

>6) Pressing Delete sends Backspace (8 decimal) instead of delete
>(127 decimal). Searching for "Delete" or "Backspace" in the manual did not
>turn up anything relevant.
>
You can send ASCII.DEL by pressing CTRL+backspace (this is described in 
appendix A.2 - I
don't know why your search didn't find this). I decided not to use the 
DEL key since it is used
as part of the editing keypad simulation (required in vt420 mode, also 
described in appendix A).
I agree this may be confusing, - I could make the DEL key work as you 
expect in vt100 mode,
but I would have to disable it again in vt420 mode. One of the problems 
with the whole keypad
emulation is that the layout of the IBM keypad is so different to the 
DEC layout that there doesn't
seem to be an obvious mapping that suits all modes.

>7) I have found a bug in reverse video handling when using TPU and MONITOR.
>When painting some areas, the area is incorrectly displayed in reverse video.
>
I'll look into it. Thanks. See last comment (below).

>9) Do you have any support for the bell ? VMS operations that normally ring
>the bell are silent.
>
Yes, the emulator supports ASCII.BEL. There must be some other control 
sequences that
cause a bell on a real vt100. I'll fix them as I find them.

>Misc questions.
>---------------
>10) Did you consider using GtkAda instead of GWindows to write the emulator ?
>This would have created something that could run on Linux as well.
>
Not really - one of the reasons for building the emulator in the first 
place was to try out
GWindows. It then got out of hand as I found more and more uses for the 
emulator
(which is why Redirect exists). I particularly wanted to try GWindows, 
since it looks very
promising as a means of making Ada more accessible to MS programmers - 
they don't
have to learn a new windowing system as well as a new language. Also, I 
think Linux
is well provided for in terminal emulation, whereas Windows is not. At 
least, not with
non-commercial solutions.

>11) If you can't write a Telnet package, is there an existing command line
>telnet that you can use from within a redirect window, or the Win98
>workaround you have for redirect ?
>
I had the same thought, and am looking into it now. I'll keep you posted.

>A final note:
>-------------
>I have only spent a few hours building and evaluating this emulator, so this
>cannot be anything approaching a full evaluation. Also problems with the
>keyboard emulation stopped me from running my usual range of tests. These
>reasons mean you need to be aware that there may be other issues that I have
>not discovered.
>  
>
>Although I cannot spend any more time on this, I hope that the above feedback
>does prove helpful for you.
>  
>
Yes, thanks. However, if you can find the time to go at least repeat 
your tests with the
emulation mode set to vt100 (which would solve a few of the problems) 
I'd be particularly
interested in any more information you could give me on the reverse 
video problem.
If you do get time, perhaps you could run the program with the 
"/displaycontrols" option
enabled, and then save the entire virtual buffer to a file and email it 
to me ?.

Thanks,

Ross.