

Retro-engineering a video game system.   - one010101
http://www.lucidscience.com/pro-lazarus-64%20prototype-1.aspx

======
wwalker3
I liked how today's low memory prices completely changed the hardware design
tradeoffs. This system uses only 1980s-level technology, but you could never
have afforded to build a bank-switched double-buffered memory system like this
for a home game console back in the day.

As a result, the animation is super-smooth and doesn't show any tearing
artifacts. Which is funny, considering that you could still see tearing on the
Windows desktop until Vista (the underlying hardware had long been double-
buffered, but operating systems took forever to make full use of it).

~~~
pvg
_but you could never have afforded to build a bank-switched double-buffered
memory system_

You mean like, say, on an Apple ][.

~~~
wwalker3
It's true that the Apple ][ was double-buffered, but as another commenter
mentioned, it wasn't a game console :)

But the Apple ][ is actually a good illustration of my point. Due to the cost
of memory back then, Wozniak had to make many compromises in the hardware
design, which resulted in a number of very odd visual artifacts. For example,
if you tried to move a colored sprite around on screen, the colors of pixels
in odd and even columns would flicker between two different four-color
palettes.

The retro-engineered video subsystem in the article is essentially the same
resolution as the Apple ][, but with greater color depth and none of the
compromises, all because the cost tradeoffs have changed so much in the last
30-odd years.

~~~
pvg
No it wasn't console, true enough. I wouldn't describe the Apple ][ display
system as memory-driven 'compromise', there were a number of factors some
being low component count and price. Within those constraints, the thing is
actually incredibly clever. It could have easily been part of a game console.
Console makers of the time, though, just used this -

<http://en.wikipedia.org/wiki/Texas_Instruments_TMS9918>

I don't think the price of memory was the main design driver of either of
these approaches.

~~~
wwalker3
I agree that component count and the price of other logic chips were important
too. Woz was a genius at that kind of design where you have to do something
super-creative to save that last tiny bit of cash.

However, I think I can make a good argument that memory price was the main
factor. As a hardware engineer, the only reason you'd ever use tricks like
indexed color (palettes), foreground/background color per character (like CGA
or the TMS9918), even/odd column color restrictions (like the Apple ][), and
all the rest is to save memory.

Once you can afford enough memory to store your full color depth for every
pixel in the frame buffer, your display hardware actually gets simpler -- it's
just a straight pipe from memory to screen with no extra logic (other than
your D-to-A conversion in the old days). No indexing, no complicated bit-
packing schemes, no switching of color palettes during horizontal or vertical
retrace.

Tons of effort and creativity went into that stuff, but it was all obsolete
once memory got cheap enough.

------
hugh3
Can we get a filter that lops "Amazing" off the beginning of all headlines?

~~~
hugh3
Wow, it worked. Thanks!

------
Keyframe
You can do this yourself (or with your kid) with XGameStation:
<http://www.xgamestation.com>

