RE: [hispamsx] Pregunta GFX9000

2000-05-29 14:32:53

    La tarjeta de serie contiene una entrada analógica de mezcla de
de video. Con sólo el GFX se puede mezclar la salida con la del MSX, y
realizar un juego que aproveche ambos VDPs.

Lo has proobado?
Me contó el facedor del Video9000 que sta entrada no era útil, ya que la
velocidad de ambas VDPs era distinta, por lo que no se sincronizaban.

Es por esto por lo qu comentaba que hacia falta un genlock para poder
utilizar ambos VDP's al mismo tiempo.

adjunto un email de Peter Burkhar (Sunrise) donde explicaba esto:

The Gfx9000 can superimpose the
image over an incoming signal,
can't it???

No, the GFX9000 can't superimpose. Although this was promised initially,
and indeed a superimpose chips is mounted on the GFX9000 board,
superimposing isn't possible.

If one tries to superimpose, just by connect an RGB signal to the
GFX9000 via the small 5-pen connector, the GFX9000 image will be
disturbed: a vertical line, drawn by the GFX9000, will become a
'sawtooth line' during superimposing upon the V9938 screen. The 'teeth'
are maximal 1 pixel width and are moving up and down with an undefined
speed, which is different on each computer.

The problem is that the V9938/58 image and the V9990 screen are not
synchronized. That means that the V9938 draws 1 screenline in let's say
64us (microseconds = 0.000001 seconds) on de cathode ray tube, but that
the V9990 draws a line in for example 63.9us. As long as these linetimes
are not exactly equal (and they never are), then you'll get this

Only with a Video9000 it's possible to superimpose the V9990 image upon
the V9938/58 screen (or upon ever other video signal). The Video9000
contains a special circuit, called a genlock, that adapts the speed of
the V9990 to the speed of the Vii38/58, so that both VDPs draw 1
screenline equally fast.

So, although a superimpose chip is mounted on the GFX9000 board, the
GFX9000 is missing a genlock circuit, and so it can't superimpose

Besides, there is a second possibility, only suitable for NMS8280 and
Sony900 owners (I take the NMS8280 as an example):

The NMS8280 also has a genlock on board of course (otherwise
superimposing wouldn't be possible on this computer either). Now, this
genlock can be used to synchronize the V9990 and the V9938. In this
situation the V9938 speed is adjusted to the V9990 speed, instead of the
other way around (like done in the Video9000).

The trick is as follows:

Connect the RGB output (SCART) of the NMS8280 to the small 5-pen
connector, that is mounted on the GFX9000 PCB internally (somewhere on
the edge of the board).

Connect the RGB output (SUB-D connector) of the GFX9000 to the RGB input
of a SCART splitter or distributor (such a thing that is used to connect
more than one monitor or TV to one computer: one RGB input, several RGB

Connect the first RGB SCART output of the splitter to your monitor
(using a SCART-SCART cable). Connect the second RGB SCART output of the
splitter to the Video in plug at the rear side of the NMS8280 computer
(using a SCART-CINCH cable, the CINCH plug should be 'Video out').

Type on your NMS8280 compueter: SET VIDEO 1,0 and select the CINCH Video
in plug of the NMS8280 by means of the switch on the frontpanel. Now the
V9938 is running at exactly the same speed as the V9990 -> superimposing
has become possible.

You see, just a lot of work, and only suitable for people that have a
genlock (NMS8280, Sony900). A Video9000 is much more convenient, and
besides it can also superimpose upon other video signals than just the
V9938 screen (and it can digitize as well).

If that's so then you can create
a game/program showing

Correct. I myself have made a little demo once, in which I made six(!)
layers scroll upon each other. From back to front:

0) de background of the V9938 (one colour, not a real layer)
1) de bitmap layer of the V9938 (frontimage)
2) the sprite layer of the V9938
3) the first pattern plane of the V9990 P1 mode
4) the first sprite layer of the V9990 P1 mode
5) the second pattern plane of the V9990 P1 mode
6) the second sprite layer of the V9990 P1 mode

I have an NMS8280, so I could make the background tranparent, and
superimpose the whole stuff upon an external tv image.

Was the salesman clueless? Productopia has the answers.

*HispaMSX. La mailing-list de MSX en castellano*
Para cualquier duda: msxjam(_en_)crosswinds(_punto_)net

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