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History of Viewfinder revealed

By Chris Williams. Published: 14th Nov 2005, 07:16:47 | Permalink | Printable

Plus schematics

ATi graphics cardThe story behind the development of the Viewfinder, the kit that interfaces an AGP graphics card to the Acorn podule bus, has been revealed online by developer John Kortink. According to the guide, the expansion card uses an Altera programmable chip to act as the glue between the two buses and to perform the colour byte swapping for the RiscPC's BGR format.

The driver software however is the most complex component, as John needed to control the AGP card without any help from the operating system or BIOS, and with limited documentation from ATI. He also had to write an x86 emulator so that the ROMs on the AGP cards could be executed. This was before extra features such as dual head capability and graphics acceleration were added.

The Viewfinder card supports the ATI Rage Pro, Rage 128 and Radeon cards, although it is now no longer available for general sale. Many users regard the Viewfinder as a significant upgrade for the RiscPC.


Viewfinder website

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A very interesting document. What a top job to do all that!

 is a RISC OS Userharmsy on 14/11/05 9:15AM
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I wonder if the ViewFinder will remain "History", or a return is planned?

A friend has ViewFinder, he found it quite good except when using !Sibelius music software when the ViewFinder and MIDI card would not work together.

I recall he said something about having to disable (turn off) the ViewFinder to run the MIDI.

 is a RISC OS UserSawadee on 14/11/05 9:22AM
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sawadee: I don't see much point in using a viewfinder in a podule-equipped iyonix. And it has nowhere to go on an A9. Looks like history to me. -- Sprite

 is a RISC OS UserSpriteman on 14/11/05 1:06PM
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ViewFinder may be history for new machines such as Iyonix and A9, but since RiscPC's still appear to be blooming (according to recent surveys), there's still a lot of employment for ViewFinder. Its capabilities are really superb, and I still miss the brilliant way of defining new and always perfect screen modes, without fiddling and mudding with CustomRPC or similar tools on my Iyonix.

Paul Sprangers

 is a RISC OS Userdelink on 14/11/05 1:43PM
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And the Radeon cards used are a lot cheaper now, than they were back then. If the top ViewFinder was available now for a quarter of its former price, I guess it would be quite popular.

 is a RISC OS UserJGZimmerle on 14/11/05 2:54PM
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But only a small part of the cost was in AGP card!

 is a RISC OS UserCJE on 15/11/05 11:46AM
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Of course the biggest part of the cost was in the development work John put into it, but I thought he had written that off, so might be persuaded to let someone make a cheap version of it.

 is a RISC OS UserJGZimmerle on 15/11/05 7:25PM
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I would love to see a cheap version of the Viewfinder (I'd certainley buy one) - It's unberable going back to my Adjust'd RISC PC after using an Iyonix at 1280x1024 in 16 million colours

 is a RISC OS Userleeshep on 15/11/05 10:34PM
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