[A89] Re: A Night's Pondering...


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[A89] Re: A Night's Pondering...




> it would be interesting to see whether or not it could emulate in real
> time.

It would be interesting to see if people would stop proposing stupid ideas
like this when they lack the technical knowledge to assess the feasibility
themselves, then try to disagree with people like Niklas who DO have that
knowledge (and Niklas: no, I wasn't the one who wrote that, but I remember
it as a simple explanation of why it could never work).

> i think the only difference between the gameboy's processor and the
> z80 are the scrolling registers and the sound registers,

The ix and iy registers are not present in the DMG/CGB's z80 clone, and
stack access is very different.  IIRC, sound is controlled by ports, not
registers, on the DMG/CGB.

> also i dont know if its rom routines or part of the processor's routines
> but it uses a system somewhat like grayscale in order to display multiple
> planes for scrolling backgrounds and sprites.

The graphics routines are part of the hardware (as in a chip, not code in
the ROM).  DMG/CGB sprite-based graphics work very, very differently from
the memory-mapped TI calcs.  Emulating that alone would be a feat.

> it would be kinda hectic to implement grayscale in with this though
> because you would end up with about 8 planes to work with

Or zero planes, because the GBA's grayscale isn't plane-based.  We all know
how hectic it can be to write a program that uses zero or so planes at once.

> for a one plane game with b&w like pong it probably wouldnt run too bad,

Once again, the concept of using two planes to create grayscale does not
exist on the gameboy.  All games are inherently grayscale.

> i havent tried texzas but if it runs fine on the 89 then it might be able
> to work in realtime with the modified registers, etc... who knows?

Your original flaw was assuming that if tezxas worked, then so could other
z80-based systems.  Tezxas itself is an amazing piece of work, but it's
still not comparable to a real ZX Spectrum, particularly because of the calc
s' low resolutions, which would also be a critical issue in gameboy
emulation.  Samir himself acknowledged that emulating a gameboy is not
feasible because a gameboy is so much more powerful than a ZX Spectrum.

> zshell...anyway i dont think it can be proved that gameboy absolutely cant
> run decent on an 89 until someone really tries it

Sure it can, but anyone with sufficient technical knowledge to understand
the proof will realize it's so blatantly obvious they don't need it.

> as a mentioned before the smallest cart is 16k but that is padded with 0s

Actually, they're padded with the opcode for nop.

> to be a multiple of 16k, so for the emulator you can strip those off and
> end up with games that are only a couple of k... but for games besides
> asteroids, pong, defender, etc theres no way possible

News for you: the DMG/CGB versions of all of those games are well over 16k.
If the games were so simplistic that they fit in a few k, then they wouldn't
sell, which is why you don't see the generic arcade clones on the gameboy,
but instead all kinds of enhanced versions.

----------------------------------------------------------------------------

What you're trying to tell us is equivalent to a first-grader saying that
because we can go to the moon, we can go to Alpha Centauri.  The first
grader doesn't know much about how space flight works; you don't appear to
know much about how emulation works.  The gameboy is much more powerful than
a ZX Spectrum; a ship capable of transporting man to alpha centauri would be
much more powerful than one to take us to the moon.  And even at the most
visible level, there are obvious incompatibilities: the Apollos' propulsion
system would obviously be different from one that could travel to another
solar system, and the gameboy's display model is completely different from
the calculators' displays.

I reeeealy don't want to waste my time explaining all the reasons why it
can't be done, which is why I was hoping a simple "No" would have sufficed.
Apparently not.  You can keep trying to tell us it's possible if you like;
but it's not, and it won't be done.  If you're really so sure it can be
done, then go do it.

    -Scott





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