Subject: Re: Tiga chip

From: Pat Mackinlay <[email-masked]>
Date: 27 Jun 1993 01:34:45 +0800

[...sorry if I repeat something already mentioned here, I had a stupid
sysadmin stuff up my mail and I've only just fixed it. Is this list
being archived anywhere?...]

>-60 Mhz TMS34010 graphics processor.  7.5 Mips 32 bit general pupose and 
>	graphics processor.
>-1024x768 non interlaced resolution with 256 of 16.7 million colors.
>	maxmimum 1 MB dual ported VRAM and 1 MB DRAM

>Not sure if those limited are the boards' of the cpu's.

The performance I think is pretty much a limit on the chip. As far as
I remember, you can get 40, 50 or 60 MHz versions of the 34010, but it's
_not_ a fast chip. The actual display I'm not so sure on. If I remember
right, the '10 supports up to 16 bit pixels, while it's big brother,
the 34020 supports full 32 bit pixels. In any case, I think the size
of the screen is purely limited by the amount of video memory you
attach to it. Again, I could be wrong, but I think the '10 has a 24 bit
address bus, meaning you'd be "limited" to 16 meg of RAM.

>Would this be better/more cost effective then say a mips chip?

It won't be faster than using a dedicated MIPS chip to do graphics,
but I _know_ it will be cheaper. The big cost savings are that it
generates _all_ the signals required to drive a monitor, and it
integrates very smoothly with the host CPU.

>I volunteer to try to get a driver written for this card, I think
>we may even have documentation around.

I don't think using a Tiga video card would be a very wise idea
personally, they cost quite a deal of money. I think we can do quite
well if we can stick a 34010 + VRAM on the motherboard - writing a
driver for the chip won't be easy, but surely not too much more
difficult than for a dumb frame buffer. I think the big problem as
far as code goes is that GNU C (for example) doesn't support the
chip, and getting tools that do could be quite a challenge...

I promise to go and do some reading on the chip, and I should have
some more concrete info soon. Can someone find out pricing info from
TI in the States? Hopefully, the chip will only be about US$40 or
$50, making it a pretty good candidate for the system. Oh yeah, and
if someone _does_ ring them, you might ask them about the 34020 and
the floating point unit for the chip (forget the number). I'm not
suggesting that we should worry about either of these two chips, I'm
just a little curious.

BTW: I wouldn't expect that using a 34010 would make the graphics
system outperform any of the VGAs out there, but it'd be quite
interesting, and would leave the main CPU free to do some "real"
work. It might even be practical to run PEX stuff <grin>

[...if there is no archive site, would someone be willing to mail me
the last day or two of messages? I don't like having to repeat questions
that people have already answered...]

Pat -- "There's only one thing left to do Mama, I got to ding a ding dang
	my dang a long ling long" (Jesus Built My Hotrod -- Ministry)
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