New game convertions!

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Por PingPong

Prophet (3912)

imagem de PingPong

08-12-2007, 20:57

Another release, this time from Amusement Factory... Karateka!
What marvellous piece of s .... t, congrats to the original game developer. :P:P:P:P:P:P:P:P:P:P:P:P:P:P

Por spl

Paragon (1470)

imagem de spl

09-12-2007, 10:39

Another convertion!!! Great!! Big smile

PS: I played it a lot in a old XT PC when I was a child at a friends home Smile

Por ARTRAG

Enlighted (6864)

imagem de ARTRAG

09-12-2007, 10:42

I do not know, you but I find it unplayable
oO

Por spl

Paragon (1470)

imagem de spl

09-12-2007, 11:05

Even the original version for PC was very difficult, but in 1984 was a real game hit. This game was made by Jordan Mechner, who created 5 years later of Prince of Persia.

http://en.wikipedia.org/wiki/Karateka_%28computer_game%29

Por PingPong

Prophet (3912)

imagem de PingPong

09-12-2007, 12:40

@Fudeba:


MSX has many things that slow everything down. I had already explained several times that even without the need of sending data to VDP... MSX would be slower than Speccy. Speccy doesn't have an extra wait state on every M1 cycle as MSX does (from MSX1 to turboR in Z80 mode).

But it has contended vram access, do not forget... speccy guru's know about of this.... so when the z80 writes to vram the ULA slow down the cpu...

Por PingPong

Prophet (3912)

imagem de PingPong

09-12-2007, 12:47


Colors are less complicated than patterns. Usually the processing is conversion using a table and then outputing 8 times the same value... this way, the "overhead" is not that critical. I found it curious why the programmers had chosen to statically convert the colors and left the pattern conversion to be made on-the-fly. The only reason I could find is that it would be too complicated/complex and would require rewrite so many parts of the game that it couldn't be justified... on a conversion. Maybe it would be better to rewrite the entire game (and the programmers probably were not paid to rewrite the entire game).

I agree. with color it's a most simple situation, however the having to output 6144 instead of 768 bytes (even if all equal) does impact severely on performances. Plus consider that we can not do things like this.

ld a, (HL) ' assuming HL pointing to zx attr table
out (0x98),a
out (0x98),a
out (0x98),a
out (0x98),a
out (0x98),a
out (0x98),a
out (0x98),a
out (0x98),a

because the vdp cannot cope with this. otherwise maybe we need something like this:
out (0x98),a
nop
nop

X 8 times

this slow down the performances at the same level of about pattern blitting....
Tongue

Por Manuel

Ascended (18958)

imagem de Manuel

09-12-2007, 13:06

Fudeba: Karateka's Curiosity page on your site is still in Portuguese only?

Por Fudeba

Expert (113)

imagem de Fudeba

09-12-2007, 22:49

I do not know, you but I find it unplayable
oO

It's only really playable on turbo R or 7MHz mode. In fact, it was unplayable even on ZX Spectrum native version. It was a surprise it became playable on MSX @ 7MHz. Tongue

Por Fudeba

Expert (113)

imagem de Fudeba

09-12-2007, 22:57


But it has contended vram access, do not forget... speccy guru's know about of this.... so when the z80 writes to vram the ULA slow down the cpu...

I am not a Spectrum master, but I had always assumed the slow down on Z80 by ULA was only during the screen update by ULA ... and most games seem to avoid writing/reading VRAM on these moments (some games seems to write during screen update to create the 'snow effect', though).
Anyway, it's very hard to compare both hardwares. But I completly agree with you that is those games were re-written for MSX, using directly its resources, MSX @ 3.57MHz would be able to reproduce Spectrum speed.
Too bad this practice was the exception... not the rule.

Por Fudeba

Expert (113)

imagem de Fudeba

09-12-2007, 23:01


Plus consider that we can not do things like this.
ld a, (HL) ' assuming HL pointing to zx attr table
out (0x98),a
(...)
out (0x98),a
because the vdp cannot cope with this. otherwise maybe we need something like this:
out (0x98),a
nop
nop
X 8 times
this slow down the performances at the same level of about pattern blitting....
Tongue

Well, I discovered in the 3 or 4 past years that, in fact, these nops are needed
only on computers using TMS9128 (or V9918, or V9928). When the computer uses
V9938 or better this is not required; Most games I adapt or improve has two VRAM
writing routines; one for MSX1 computers, with the NOP delays and another for
MSX2 or better, without the delays.
The speed improvement is not huge, but it is not small either.

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