V9958 RGB output timing specifications ?

Por Ragooman

Supporter (4)

imagem de Ragooman

25-01-2010, 08:36

Hello,

I'm looking for the V9958 RGB output timing specifications. I have only one version of the datasheet for this chip, it's only 34pages. So some of the information in this is limited.

I'm trying to find out what the video timing specifications are for the RGB output. I noticed that some people mentioned on this forum that it's possible to use some of the newer LCD monitors. I was wondering if it's possible to use a regular VGA monitor(crt).

These were all multi-sync monitors, so I'm curious as to what video timing is coming out of this chip. I tried looking at the service manuals for the MSX2+ and Turbo computers but they are all in Japanese - and I'm afraid I don't know anyone that can read this.

thanks
=Dan

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Por Manuel

Ascended (19270)

imagem de Manuel

25-01-2010, 09:34

15kHz... I don't know any VGA monitor that goes that low.

Por Ragooman

Supporter (4)

imagem de Ragooman

25-01-2010, 12:53

15kHz... I don't know any VGA monitor that goes that low.

Even when using the 512x424 interlaced resolution ?
I work with arcade monitors and this comes close to VGA timing.
I don't see how a 15khz monitor can still display this hi-res screen mode.

Por NYYRIKKI

Enlighted (6016)

imagem de NYYRIKKI

25-01-2010, 14:58

I think the maximum resolution for NTSC is 858 x 525 and for PAL it is 864 x 626, so MSX picture fits in nicely in all cases.
Normal TV's don't like too much changeing sync, so all screenmodes use 15KHz timing.

Por Ragooman

Supporter (4)

imagem de Ragooman

25-01-2010, 16:23


I think the maximum resolution for NTSC is 858 x 525 and for PAL it is 864 x 626, so MSX picture fits in nicely in all cases.
Normal TV's don't like too much changeing sync, so all screenmodes use 15KHz timing.

This chip has RGB output only. TV 's here in the USA don't have RGB, but I recall that those in Europe and Japan offered this back then and probably still do using the SCART connector.

If it only has 15.7khz horz rate, it sounds like you still want to use a RGB signal in 512x424 screen mode to retain the signal quality versus converting to a Composite video signal, correct ?

From what I read, the max res for NTSC is 536 x 525
http://www.maxim-ic.com/app-notes/index.mvp/id/750

But the actual screen display resolution is smaller.
According to that link, it's 451 x 438 for NTSC-TV
And for PAL-TV , its 538 x 576

Some of the posts on this forum mention they use one of the LCD monitors which have a SCART connector, can sync to this screen mode.

Is this the only way to hookup a MSX2+ or Turbo computer ?

Por NYYRIKKI

Enlighted (6016)

imagem de NYYRIKKI

25-01-2010, 17:01

I think your link must be wrong because the MSX picture is displayed without problems and even the TV stations send with much higher resolutions you are talking about. How ever I'm wrong person to argue about these kind of things. This is not very clear to me either. I just know that MSX display looks good when connected to TV with correct cable. Tongue

I usually hook up my MSX tR with SCART to TV or CRT monitor or then I use S-Video to connect it to video projector. The older MSX tR model has composite output, but MSX tR does not have the RF output anymore. I consider composite and RF output to be too poor quality for high resolution screen modes. For example you can still read 80-column textmode, but it gets quite a soft.

From my experience I would say that connecting MSX tR to LCD is not usually the best possible solution. You might end up with all kind of trouble & graphical glitches because of the scaling... It very much depends of what kind of scaler the display has. I think best is to use SCART & something like 14" good old CRT monitor. That gives really nice looking picture. Too sharp image for V9958 resolution does not look good either... This is why modern emulators have plenty of options to worse the image quality Smile2

BTW I've made a pretty good display test program for MSX (V9938 & V9958) Mail me if you need it. It tests the graphical glitches that you might end up when connecting to LCD and CRT.

Por Ragooman

Supporter (4)

imagem de Ragooman

25-01-2010, 18:43

Yes, from what I read using the SCART connector makes a big difference by interfacing the RGB signals directly to the TV. I remember this connector from when I was stationed in Europe during the 80's, it did make a big difference.

I have to find something here that will be compatible. I have 19" Arcade RGB monitors here, which are 15khz, and so I thought maybe it's possible to display on this too.

I like to see the test images that you prepared. I sent a message to you about this.

Por Metalion

Paragon (1622)

imagem de Metalion

26-01-2010, 07:18

1. The max resolution for normal TV is the one used for the DVD specs :

- 720x576 for PAL
- 720x480 for NTSC

Both are interlaced, of course.

2. VGA monitors do not go lower than 31KHz, and cannot display MSX picture without the help of a scaler

Por NYYRIKKI

Enlighted (6016)

imagem de NYYRIKKI

27-01-2010, 22:04

I've sent you my monitor test program.

Por Gradius2

Hero (652)

imagem de Gradius2

11-02-2010, 17:12

If you want all the exactly correct stuff, just look at V9958 spec diagram.

You can just look at V9938 diagram, there is no much difference between two.