allen@grebyn.com (Allen H. Farrington) (07/17/90)
Video DMA / Hardware Guru's:
Prolog: I define RS343, 875-line video as 809 lines by 1080 columns at
60Hz, 2:1 interlace, and 4:3 Aspect Ratio giving a total of 873720
pixels (active, of course.)
Would it be possible to generate (with a stock Amiga (2000 or 3000)) an
RS343, 875-line Video output? Adding a card would be ok, but no mods
to the motherboard are allowed. Another requirement is that the machine
must be usable normally except when the actual 875-video is displayed.
In looking at the hardware specs for the A2000, I wonder if you could
disable the normal DMA for the audio, sprites, and video and have enough
time to get four bit-planes worth of video out of the machine.
Is this more likely with an A3000 or is it do-able with an A2000 and the ECS?
What is possible with the programmable modes of the ECS Denise?
Any takers?
--Allengrr@cbmvax.commodore.com (George Robbins) (07/19/90)
In article <20419@grebyn.com> allen@grebyn.com (Allen H. Farrington) writes: > > Video DMA / Hardware Guru's: > > Prolog: I define RS343, 875-line video as 809 lines by 1080 columns at > 60Hz, 2:1 interlace, and 4:3 Aspect Ratio giving a total of 873720 > pixels (active, of course.) I think the basic answer is No. The ECS chipset is pretty much maxed out at a 28 MHz dot clock and 31 KHz scan rate. Your spec seems to exceed this by a good bit. -- George Robbins - now working for, uucp: {uunet|pyramid|rutgers}!cbmvax!grr but no way officially representing: domain: grr@cbmvax.commodore.com Commodore, Engineering Department phone: 215-431-9349 (only by moonlite)
raible@cbmvax.commodore.com (Bob Raible - LSI Design) (07/19/90)
There is no reason that an external card couldn't do this by bypassing the Amiga video chip set and dma'ing out of memory. As George said the main problem with an internal solution is that we can't generate pixels finer than 35nSec. Agnus can probably generate the RS343 timing signals okay, its just that you wouldn't get that many pixels on the screen. What I'm pointing out is that we can probably support the standard by putting out a display , albeit a rather coarse one. Hope this helps.