ANSI behaviour

ANSI behaviour

[K. Reid-Grey]

I've been using DOSemu's "virtual" com ports to run a bunch of BBS doors
under Linux and I've noticed the output appears a little different because
of the way the terminal behaves to some ANSI sequences compared with real
DOS.

In MS-DOS ESC[2J clears the screen /and/ homes the cursor while terminal
clients only clear the screen. This means the next screen is drawn from from
the bottom row of the previous one, scrolling the screen.

It's only a small cosmetic thing I know, but I was wondering if anyone knows
of a way I can setup the terminal to correct the display, or perhaps filter
the "virtual" com port data on the fly to append a 'home cursor' sequence.

---
K. Reid-Grey

Re: ANSI behaviour

[Ged Haywood]

Hi there,

On Fri, 21 Feb 2003, K. Reid-Grey wrote:

> In MS-DOS ESC[2J clears the screen /and/ homes the cursor

Isn't that because you have the ANSI.SYS device driver loaded?

Can't you just load it in your DOSEMU session?

73,
Ged.

Re: ANSI behaviour

[Ged Haywood]

Hi there,

On Fri, 21 Feb 2003, K. Reid-Grey wrote:

> > Can't you just load it in your DOSEMU session?
> 
> It's loaded in there too, but it makes no difference either way.

Argh.  I found this in the doc's...

----------------------------------------------------------------------
8.1.2. ms_dos

   int0x21 call
   
   we trap this for two functions: simulating the EMMXXXX0 device and
   fudging the CONFIG.XXX and AUTOEXEC.XXX bootup files.
   
   note that the emulation herein may cause problems with programs that
   like to take control of certain int 21h functions, or that change
   functions that the true int 21h functions use. An example of the
   latter is ANSI.SYS, which changes int 10h, and int 21h uses int 10h.
   for the moment, ANSI.SYS won't work anyway, so it's no problem.
----------------------------------------------------------------------

There are other device drivers that do similar things, maybe there's
one that will work?

73,
Ged.

Re: ANSI behaviour

[Ryan Underwood]

Hey,

> I've been using DOSemu's "virtual" com ports to run a bunch of BBS doors
> under Linux and I've noticed the output appears a little different because
> of the way the terminal behaves to some ANSI sequences compared with real
> DOS.
> 
> In MS-DOS ESC[2J clears the screen /and/ homes the cursor while terminal
> clients only clear the screen. This means the next screen is drawn from from
> the bottom row of the previous one, scrolling the screen.

Yep, this is a quirk of the MS-DOS console driver.  The only way around it
really is to use a terminal emulator that supports it.  I have hacked support
for it (along with some other DOS quirks, like printing control characters
< ASCII 32 from the video card ROM) into PuTTY so that the Unix pterm would
support them, but the author wants a more cleaned up version of the patch
first.  :)

-- 
Ryan Underwood, <nemesis at icequake.net>, icq=10317253