Archived from groups: rec.games.video.arcade.collecting (
More info?)
On 18 Apr 2005 08:26:43 -0700, in msg
<1113838003.777743.52870@z14g2000cwz.googlegroups.com>, "seanm"
<dseanmaclean@gmail.com> wrote:
>As far as i can recall (not having played an original upright for a
>while) everything seems to be there sound-wise. When you power up you
>get the constant 'star trek' tricorder sounding pulse. Explosions and
>lasers all sound good. I don't recall thinking that is was any
>different.
Mine is definitely different by design. On mine, the soundboard is not a clone
of the original Star Castle soundboard. But I never delved in far enough to
figure out if the deep bassy throbbing sound, that get faster the longer you
play, was missing because mine's broken, or whether they simply left out. At
first glance it looked like they simply left it out.
>It is really hard to get the vectors to line up for sure ...
>mostly shows up on the text. I have to game play pretty close now
>though after swapping out the op-amps ... close but still not perfect
Yeah, the vector electronics on the clone is a much simpler design, using
cheaper parts, they left out anything not needed to draw a vector, apparently
this included some linearizing circuits.
To be fair, it's impossible to get the vectors to line up perfect on the
original Star Castle design as well. To do that the engineers would have
required a fast (hardware) divider, which would be way too expensive in the
80's, so to normalize vector DAC voltages and to calculate vector draw times,
they used shift registers. A decent compromise, but definitely not perfect, most
noticeably at the shift register boundaries.
Atari had to do a similar thing in their vector generators. This affected ending
points in their AVG, similar to how it affected the Cinematronics stuff. Atari's
DVG (Digital Vector Generator -- used in Asteroids & Lunar Lander I think) drew
vectors using digital counters on DACs, so their endpoints match up perfectly,
but the shift register errors caused different angled vectors to be drawn at
different speeds, so some angle vectors were drawn slower, making them brighter,
than other angles. You can see this by looking at the different intensities of
the asteroids' sides. Once again this is because they didn't have a fast
hardware divide.
Ok, I'm done with the off topic free associating ramblings...
-Zonn
--
Zonn Moore Run MAME's vector games on a real
Zektor, LLC vector monitor using the ZVG!
www.zektor.com More info at: www.zektor.com/zvg
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