The TI 34010

From: Derek Peschel <dpeschel_at_u.washington.edu>
Date: Tue Mar 2 21:06:59 1999

> IIRC, some suns have a bitmapped screen, but no hardware support for
> combining bitmaps. The CPU has to fetch a word from video memory, flip
> the appropriate bits and write it back.
>
> That's one reason why Suns were cheaper than PERQs all those years go...

I think the console-mode code is also very simple. One Sun I used (not sure
what kind, but it was probably < 10 years old) took 1-2 seconds to invert
the screen in console mode but ran X quite normally.

> Text modes on different PC graphics cards were pretty compatible. All
> cards had a 4K text memory area, containing ascii codes and attributes in
> alternate bytes. The attributes did vary between mono and colour cards,
> but were actually somewhat related. Mono cards had the memory at one
> address, colour cards at another address, so you can have one of each in
> the same machine.

Well, I guess I'm thinking of the VGA which may not be what you had in mind.
There are two kinds of "extra" mode:

Modes you get by tweaking the registers, and which any compatible VGA card
should be able to do. (e.g., 80x43, 80x50, a few other ways to combine
character sizes in pixels and screen sizes in scan lines; also 512-character
sets, bright backgrounds, underlining in color). I think some of those were
even on the EGA.

Modes only certain manufacturers give you (usually because of extra
screen resolutions the card can produce, possibly because of extra character
sizes -- I think one card has 8x9 characters, and I may have read about a
90-column mode somewhere).

Then of course there are entirely different graphics cards which is kind of
a separate subject.

My main complaint is about the software rather than the hardware, as I think
I pointed out. In DOS, you can DO whatever you want (if you can find the
documentation and if you know the card will handle it) but the OS has no
concept of it. In Windows NT, the OS has a concept but it's VERY limited.
I think the console API only promises 16 colors, which is pretty pathetic
since even the EGA gives you a palette of 64. In my experience, NT just
makes the situation too unreliable.

I changed the subject from hardware to software when I started talking about
end vs. means (in the last message). Sorry if you didn't pick up on it.

Having the computer KNOW what you're doing with the video (as the Amiga and
Acorn do) is much better.

As I said, I changed the subject on you. I realize
>
> Just because nobody has defined the font you want, it doesn't mean you
> can't have it. There is nothing to stop you having an
> X/windows/Mac/PERQ/Sun/whatever font that contains the same bitmaps as
> the VT220 character generator (well, DEC's copyright would probably
> prevent it, but there's no _technical_ reason).

As I said, I changed the subject on you. I realize it's possible and I
just haven't found (done?) the answer yet.

Actually, the font doesn't have to be EXACTLY the same. But the glyphs have
to be the same shape. That's mostly a dig at Windows and Windows terminal
emulators. CRT and Ewan have trouble with the VT*1*00 line-drawing
characters (and sometimes the ISO Latin 1 characters, depending on the
font I use). Actually, this whole message is degenerating into a rant
against Windows. Maybe I should stop now.

> > Does your clone card have color? What about its text modes?
>
> No, just a plain mono Hercules card. It has the standard 80*25
> MDA-compatible text mode and a bitmapped graphics mode. That's all.

Oh. IIRC, the real Hercules offers one resolution in text mode (9x16 pixels
per character times 80x25 characters = 720x350 resolution) and a different
one (720x348?) in graphics mode. I always thought that was strange.

-- Derek
Received on Tue Mar 02 1999 - 21:06:59 GMT