[comp.terminals] 9600 baud problems

nathan@mit-eddie.UUCP (06/15/87)

In article <1166@osiris.UUCP> jdia@osiris.UUCP (Josh Diamond) writes:
>Worst problem ever seen:
>  At an unnamed computer center there are several microterm terminals
>(vt100/vt220 compatible), and several DEC-GiGi's.  Obviously everyone
>prefers to use the microterms.  So one day I go there to do some work,
>and I discover that all of the microterms are in use.  So I go to a
>gigi.  I start up emacs, and discover that every time the screen is
>rewritten, emacs decides it wants to search! Why? because the GiGi's are
>so inept that they can't really hand 9600 baud (after all, their
>terminal logic is written in inerpretive basic!!).  So, they tell unix
>to stop sending data so they can catch up, using ^S/^Q.  But emacs
>interprets this as a search. &%$%*^$*&)^^%&-up eh?

I've had very similar problems repeatedly when using an h19 (in
h19 mode). When ever certain screens were displayed, emacs would
begin to start searching for what seemed like random strings of
control characters and beeping repeatedly. I would often have to
hit ^G 4 or 5 times before it would stop. And of course the screen
was not drawn properly, so I have to redraw it...and often the same
thing would happen again.

I had decided that the problem might be that the h19 couldn't really
handle 9600 baud (as described above for the gigi), since it would
explain most of the behavior I experienced, but it seemed a little too
far fetched.  Since I thought h19's are/were fairly widely used, and
regarded along with others like vt100's as a standard terminal type, I
would expect it not to have such problems.

Does anybody know whether this is indeed true of h19's?
-- 
				Nathan Glasser
				nathan@mit-eddie.uucp (usenet)
fnord				nathan@xx.lcs.mit.edu (arpa)
"A tribble is the only love that money can buy."

rwa@auvax.UUCP (Ross Alexander) (06/16/87)

In article <6090@eddie.MIT.EDU>, nathan@eddie.MIT.EDU (Nathan Glasser) writes:
> I had decided that the problem might be that the h19 couldn't really
> handle 9600 baud (as described above for the gigi), since it would
> explain most of the behavior I experienced, but it seemed a little too
> far fetched.  Since I thought h19's are/were fairly widely used, and
> regarded along with others like vt100's as a standard terminal type, I
> would expect it not to have such problems.
> 
> Does anybody know whether this is indeed true of h19's?

yes, it is indeed true.  the h19 firmware is, to put it tersely, sh*t.  OK,
that's a little strong - apologies to JGL (or whoever; I don't have my
source listings handy :-).  But the truth is that the ROM's are clunky, to
say the least.  They treat the z80 as though it was an 8080, for a start.

there are two fixes.  one is hardware; it is relatively simple to speed up the
clock on the z80 to 3 MHz and thereby pick up some speed.  i never had any
trouble with this on my h19 (part of my h89, actually).  the other is to
chuck the stock ROM's and replace them with something a little closer to
good code.  i borrowed a ROM from someone once that sped things up quite
a bit and also did pretty fair vt100 emulation (sans 132 column, of course)
but i can't remember the vendors name.  i will dig around a bit at home
and see what i can come up with.

btw, heath/zenith will sell you a listing of the ROM.  it is well commented
and very complete (i know 'cause i typed it in and assembled it, and then
hacked it up for my own use).

...!ihnp4!alberta!auvax!rwa	Ross Alexander, Athabasca University