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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: keropi on November 18, 2005, 09:27:07 AM

Title: Do pci TV-Tuner cards need DMA? (G-Rex 1200 1st rev.)
Post by: keropi on November 18, 2005, 09:27:07 AM

Wwwweeeellll....
I will install a Fusion878a tuner on my G-Rex, but unfortunately it's the 1st version, so it only has 1 proper DMA pci slot, currently hosting an ess solo-1 soundcard. Will a tuner card work on a non-dma pci slot? or will it have problems?
I remember that I checked in windows a phillips 7134 based card and it did not report to use a dma channel, but this is amiga and a different chip...
So?  :-?  :-?  :-?

Title: Re: Do pci TV-Tuner cards need DMA?
Post by: spirantho on November 18, 2005, 10:10:59 AM

Yes, TV cards are heavy users of DMA. They actually have a processor on them which takes instructions in the form of (for example)
WRITE x PIXELS TO MEMORY AT

so without DMA the card wouldn't be able to fill the memory.

Title: Re: Do pci TV-Tuner cards need DMA?
Post by: Rob on November 18, 2005, 11:42:15 AM

@keropi
You say that your G-Rex has only one PCI slot with proper DMA, do the other PCI slots have DMA between each other.

With the Mediator there is no DMA between PCI and system RAM due to limitations with the A1200 expansion slot.  Elbox get around this by using TV-card drivers that access the graphics cards RAM using full PCI-PCI DMA.

I'm not sure if the G-Rex TV-card drivers work the same way as Elbox ones though.

Title: Re: Do pci TV-Tuner cards need DMA?
Post by: keropi on November 19, 2005, 04:55:49 PM

well, noone? DJBase????  :-?