aod@dcs.exeter.ac.uk (Anthony O'Doherty) (05/09/91)
I've just been looking through the latest edition of The Micro User, and came across something in their news pages concerning the graphics enhancer card from The Serial Port. For anyone who doesn't know, this will enable your Arc to display true 24 bit colour at a variety of resolutions. What interested me (apart from the stunning screenshot) was the file format that was being used for images produced using this board. Rather than use TIFF, they've gone for the Clear file format as used by John Kortink with Translator etc. The reason given was that Acorn haven't yet got their act together where TIFF is concerned, although they have allocated a filetype and a sprite to TIFF. What's the problem guys? The other thing that caught my eye was the mention of a VIDC2 chip believed to be on the way. Unfortunately it didn't say anything about what to expect from this, only that it would be an improvement. Can we expect to see this chip in the rumoured 'super' A3000, complete with an ARM3 and an internal hard drive for under #1000? If such a chip is on the way then would existing owners be able to upgrade? Anybody at Acorn (or elsewhere) care to comment?
nbvs@cl.cam.ac.uk (Nicko van Someren) (05/10/91)
In article <3296@izar.dcs.exeter.ac.uk> aod@dcs.exeter.ac.uk (Anthony O'Doherty) writes: ... >The other thing that caught my eye was the mention of a VIDC2 chip >believed to be on the way. Unfortunately it didn't say anything about >what to expect from this, only that it would be an improvement. Can we >expect to see this chip in the rumoured 'super' A3000, complete with an >ARM3 and an internal hard drive for under #1000? If such a chip is on >the way then would existing owners be able to upgrade? If Acorn (or ARM Ltd.) were to produce another VIDC with higher resolution as every one expects them to it is unlikely to be easy, or even possable, to upgrade to it in any sensable way becasue the real limiting factor on the Archi. at the moment as far as graphics goes is the data bus bandwidth. The MEMC can only get 25.6 MB/s out of the RAM. If you look at the dot clock rate needed to drive most multisync type monitorsit is 24-36MHz for the low resolution modes and more like 60-70MHz for the decent resolutions. Thus it is just about possable to get 8bit modes at 24MHz (needs 24MB/s) or 4bit at 36MHz (needs 18MB/s) but at 63.98MHz which is what a Taxan 795 expects for doing 1024/768 you can only get 2bits per pixel (16MB/s). If ARM Ltd or Acorn make a new graphics controler then if it is going to be worth making (i.e. does anything you can't already get) it will need a VRAM interface and it will not be possable to exploit its power on existing machines without major effort. +-----------------------------------------------------------------------------+ | Nicko van Someren, nbvs@cl.cam.ac.uk, (44) 223 358707 or (44) 860 498903 | +-----------------------------------------------------------------------------+