Re: Playing Vector Games on the Big Screen

Neil Bradley wrote:

> > > > very interesting approach, it may just work... 8-bit is actually
> > > > plenty for most vector games, and 2Mhz, is more than enough... you
> > Asteroids is Mono... (but maybe using 12-bit DAC's instead of 8-bit)
>
> 8 Bit dacs would give you 256x256, roughly 8 times smaller than the
> 1024x1024 surface area covered by the existing DACs, which would make for
> a very, very stairsteppy image. It might be good enough resolution for a
> laser system, but not a vector monitor.

we run 12-bit to 16-bit DAC's for lasers, we have a much larger screen to deal with measured in feet... and the
projector is as much as 2000 feet away

256x256 is enough for the testing for vector Monitors... but is defiently not enough all games... error in
choice of words...

Starwars 0-250,0-280 resolution would test just fine with a 8-bit DAC
Asteroids 0-1023, 128-996 resolution (using the AD561 10-bit DAC's)
Tempest 0-550, 0-580 resolution

>
>
> > > Asteroids runs at 6MHZ. I wouldn't call 2Mhz "enough"... unless this is
> > > just to drive lasers. I'm thinking vector monitors...
> > Asteroids is Mono... (but maybe using 12-bit DAC's instead of 8-bit)
> > Lets say... 500 points per frame x 60 fps = 30,000 points per second (pps) x 3 (XYI) = 150,000 distinct 8
> > bit outputs per second, or about 150KB / Second bandwidth...
>
> So are you copying this twice because of a typo or are you just being a
> smartass? ;-)

Cutting and pasting... maybe I did it twice... I am a smartass but it wasn't intentional
Now that I am home... Asteriods main processor is a 1.5MHZ 6502

>
>
> > other factors... Asteroids was Monochrome 2 color, but I think it was
> > capable of 8 shades... others like Tempest Star Wars, used 2 or 4
> > shades... so there is signifigant bandwidth reduction there as well
>
> They used color palette latches/RAM which were mapped in the 6502s address
> space. Each color was a 16 color CLUT.
>
> > and 6mhz? is that the main Processor or the State Machine Processor?
>
> The state machine processor.

Are you sure your not confusing this with the clock speed of a Raster Monitor?

For Asteroids At least... their is no second processor, but gate/latch/rom lookup table, and analog
multipliers and using a buffered clock signal from the main processor at 1.5MHZ, then their are 4 timer bits,
to set the timing of each vector wait time for the vector to be drawn...

>
>
> > the State Machine Processor drew all the vectors which it read not
> > actual vectors, but instructions on how to build the vectors from
> > shared
> > memory from the main processor
>
> Yep, I'm aware of it. I did quite a bit of video game emluation long
> before MAME was around. ;-)

I think it was 1997 when I was talking with Chris Pile about actually doing this.. and did the first test frame
for asteroids... at the time the hardware I had just couldn't handle it... and didn't really look into again
til 1999....

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Received on Thu May 30 19:46:59 2002