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- Newsgroups: comp.sys.acorn
- Path: sparky!uunet!mcsun!ieunet!tcdcs!maths.tcd.ie!merlin
- From: merlin@maths.tcd.ie (Merlin Hughes)
- Subject: Re: VIDC20!!
- Message-ID: <1992Nov10.174945.19853@maths.tcd.ie>
- Organization: Dept. of Maths, Trinity College, Dublin, Ireland.
- References: <1992Nov8.153647.27295@dcs.warwick.ac.uk> <1992Nov9.113146.12042@waikato.ac.nz> <1992Nov9.110501.1@cc.curtin.edu.au> <1992Nov9.133838.17133@wam.umd.edu>
- Date: Tue, 10 Nov 1992 17:49:45 GMT
- Lines: 34
-
- rsrodger@wam.umd.edu (Yamanari) writes:
-
- > When I read the annoncement, I was fairly impressed, but I noticed
- > that it didn't really give any hard core information.
-
- > <i.e. what is the maximum resolution at 32 bits per pixel>
-
- At a guess...
-
- Data rate @ 160Mb/second, assume no sound DMA you can get
- 160*1048576/4/frame_rate pixels on screen in 32 bpp mode.
- With a nice refresh like 80Hz, that gives 1/2 megapixel
- display = 1024*512 or 784*668. Going down to 50Hz, you
- could get 1024*818.
-
- > The other thing I noticed is that, other than the hardware cursor,
- > there was no mention whatsoever as to whether it had hardware
- > assisted graphics--i.e. bitblt, and so on.
-
- I would say it is a display-only chip, otherwise they would
- have mentioned stuff like that. What you need to do is put
- the VIDC on a graphics card, with wads of fast VRAM, and
- then you can add your graphics processor to the card. All
- the VIDC will do is display the picture cheaply, in a wide
- variety of screen configurations. The Arc (if that is your
- desired machine) will then send commands down to the card,
- and get on with its own things at no system bandwidth loss.
- The graphics processor can be an ARM or whatever. The Vidc
- can only read from the VRAM; it will never write to it.
-
- This is ignoring of course, all the mods needed to RISC OS
- and many applications.
-
- M.
-