New Undoccumented Video Mode on MSX2.

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Van Rataplan

Master (227)

afbeelding van Rataplan

09-02-2020, 09:29

I think this thread should better be locked for comments, before it escalates. This is going nowhere.

Van spacemoai1973

Master (165)

afbeelding van spacemoai1973

09-02-2020, 09:30

I think people say it's "fake" because of the claims you make. It's not a new undocumented screen mode! What you did is make a demo effect seem useful for applications. However, any application that does actual work will not be useable with this, because it requires 100% CPU time during display. Your big list of features failed to mention this important point.

Showing 224 sprites on screen is also a demo effect. Here too the limitations on sprite placement and CPU power required make it impractical. Highly technical games like Space Manbow already use more than 32 sprites on MSX, so I don't know why anyone would say it's impossible.

Btw, you have not explained why you don't post sources Wink

For anyone who wonders how this effect is done: you need two name tables, one for even rows and one for odd rows. Enable interlace in screen0. Each 4 lines toggle the name table with R#2, also you need to rotate the pattern table by incrementing the R#23 vertical offset register on every line. R#23 starts at 0 on even frames (display only even font lines) and at 1 on odd frames (display only odd font lines).

Per-line modification of R#23 can be avoided by preprocessing the pattern table to split even and odd lines. In this case you only need to set R#2 and R#23 once every 4 lines, which could be done on a line interrupt, giving your application quite a bit free CPU time. However, glitches will occur when a line interrupt is missed. In case of a miss larger than 3 lines, the whole screen will get misaligned.

I hope I didn't miss a detail in this description!

Van Vampier

Prophet (2351)

afbeelding van Vampier

09-02-2020, 09:38

Dolphin - when will you release documentation or a ROM that shows off your findings? That will silence the biggest septic Smile

Van Dolphin101546015

Champion (270)

afbeelding van Dolphin101546015

09-02-2020, 10:38

spacemoai1973 wrote:

It's not a new undocumented screen mode! What you did is make a demo effect seem useful for applications. However, any application that does actual work will not be useable with this, because it requires 100% CPU time during display. Your big list of features failed to mention this important point.

Dude, it working? It show nonstandart resolution? It possible? So, why its not New Mode? Even if its software.
This mode also not using 100% of CPU time.

VGA ModeX also half software, but Doom and other games dont think what it not will be used.

spacemoai1973 wrote:

Per-line modification of R#23 can be avoided by preprocessing the pattern table to split even and odd lines. In this case you only need to set R#2 and R#23 once every 4 lines, which could be done on a line interrupt, giving your application quite a bit free CPU time. However, glitches will occur when a line interrupt is missed. In case of a miss larger than 3 lines, the whole screen will get misaligned.
I hope I didn't miss a detail in this description!

You forgot two things:
First: you also should control and switch two Name Tables where maps anyway have 8 dots height, so you anyway need set r23, or even use 4 Name Tables.
Second: You also should control and switch two Color Tables.

Van gdx

Prophet (3566)

afbeelding van gdx

09-02-2020, 11:38

A text viewer might be interesting.

Van mars2000you

Enlighted (5635)

afbeelding van mars2000you

09-02-2020, 13:36

Dolphin101546015 wrote:
mars2000you wrote:

"To run the program I use the openMSX emulator with MSX Sanyo PHC-70F2. I load the program with CLOAD, and before typing RUN I type the following commands: CALL BC: SCREEN 0: WIDTH 80: COLOR 15,1,1. Then I type RUN and your program works perfectly. Sorry my english"

So, what you wanna show? He asqing me way, to start code IN EMULATOR. But this code nice working on my YIS503IIIR.
PS: Also, Colines variant of this program here on forum, even in .com version, for starting like screensaver for MM, with corrected settings.

Actually it works almost perfectly in a generic MSX2 machine of blueMSX, because these machines have built-in X-BASIC (it's one of the advantages that blueMSX has, compared to openMSX).
There's though a graphical glitch (accuracy bug). The only thing that must be modified in your BASIC listing before entering RUN is line 50 (by removing the REM) - that's because i keep always the machine in default settings.

Van Dolphin101546015

Champion (270)

afbeelding van Dolphin101546015

09-02-2020, 14:39

Actualy, I forgot to set starting colors, so program working, but without effects.
He set right colors, and all going as planed.
Code was tested in WEBMSX, BlueMSX, OpenMSX and on real hardware.
Corrected version here

Van PingPong

Prophet (3528)

afbeelding van PingPong

09-02-2020, 21:33

The only reason he does not share the tech details is that because there is nothing to show in a fake.
Otherwise he does at least to shutdown me and other people like me.
It Is not a childish reaction.
Hey, Dolphin What will be the next miracle? 32 sprites in a row without flickering? ????
Someone on C64 achieved 9 on a row, so do not exaggerate ????????????????????

Van spacemoai1973

Master (165)

afbeelding van spacemoai1973

09-02-2020, 21:51

It's real, PingPong. Read my posts for explanation on how it's done.

Van Pencioner

Scribe (1139)

afbeelding van Pencioner

09-02-2020, 22:21

But that's not a new video mode, that's a trick with interlacing/name table switching in old good well known 80 column text mode. So clickbait post title, that's it. And childish, really. Infantile

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