Hi,

I found a web site once which showed the differences in colour of the chips mentioned in the topic. But I lost it

Does anyone know where it is? OR is there some info about this?

Probably this page :

http://www.stanford.edu/~thierry1/ti99/tms9918a.htm

Oh nice ^_^, can someone convert those values to RGB on a 0..255 scale? I'll incorporate them in Polka2 then..

....and me in blueMSX. Interesting document.

These are just the values listed in the databook of TMS, and they represent the colors are they are output in the pins of the VDP. However, colors are further modified after that. On a Gradient Expert, for example, it passes through an analog amplifier before going to the chip that actually creates the composite video and RF signals. In the past I measured the values with an oscilloscope just at this stage. Values here are in volts. This color table includes all the non-linearity from the analog amplifiers.

index	R	G	B	Y
0	0	0	0	0
1	0	0	0	0
2	0	1.26	0.09	0.5
3	0.4	1.46	0.52	0.625
4	0.33	0.23	1.70	0.38
5	0.76	0.56	1.90	0.5
6	1.55	0.225	0.17	0.46
7	0.21	1.65	1.80	0.675
8	2.0	0.29	0.24	0.5
9	2.35	0.63	0.55	0.64
10	1.55	1.30	0.24	0.68
11	1.70	1.42	0.64	0.75
12	0	0.96	0.05	0.46
13	1.50	0.35	1.22	0.52
14	1.50	1.55	1.40	0.75
15	2.0	1.95	1.90	0.94

Interesting page indeed, but it's still not the one I remember. That one had a graphical representation of the colour differences.

Quote:

These are just the values listed in the databook of TMS, and they represent the colors are they are output in the pins of the VDP. However, colors are further modified after that. On a Gradient Expert, for example, it passes through an analog amplifier before going to the chip that actually creates the composite video and RF signals.

So, the colours would look different !?

Sure, each setup has its particular set of colors, depending on the chip (9919,9928), the analog amplifiers, the modulation system (composite or RF), the internal amplifiers of the television set, the pigments of the CRT, and user-selected settings of brightness and tint. In the end, you must consider that even differences in the human visual system can change the perception of the color, for instance, there are msx users with daltonism.

The best approach for emulation, in my point of view, is just to present the user with 15 sliders and let her set the colors she likes most.

Quote:

....and me in blueMSX. Interesting document.

Is TMS9118/9 Coleco VPD (and some MSX1) emulated by BlueMSX? Is it possible to find documents like above mentioned talking about this other chip? It has also a different palette and other significative diferences ( no timming clock).

wasnt color 1 1.1.1?

Does anyone know where i can get a supply of TMS9929NL VDP's?

Here's another interesting page :

http://junior.apk.net/~drushel/pub/coleco/twwmca/wk961118.html

Quote:

Is TMS9118/9 Coleco VPD (and some MSX1) emulated by BlueMSX? Is it possible to find documents like above mentioned talking about this other chip? It has also a different palette and other significative diferences ( no timming clock).

There are quite a few differences between the MSX1 and MSX2 VDPs. Some are emulated in blueMSX (about the same as are implemented in e.g. openMSX). Here are a few differences I can think of that are easy to test:

0. The number of registers are different (well, don't need to state the obvious maybe ) but it is emulated in bluemsx (and openmsx, and ....)
1. Palette - one MSX1 palette is emulated in blueMSX.
2. VRAM refresh - Can be turned on/off. This is emulated in blueMSX but might have a bug as pitpan pointed out earlier
Some not yet emulated differences:
3. IO Read/Writes have quite different timing. (on MSX1 they are fast outside the draw area and slow inside)
4. Sprite collision bits behave different (e.g. collisions are registered on early clocked sprites that are not visible)
5. The time from V-INT to data is outputted on the color bus is quite a lot different between MSX1 and MSX2 (almost one scan line difference)
6. The sync between the RF modulation and the color bus seems to be not as good on an MSX1.

I probably have more items to put on the list. Some of them will be emulated in the next bluemsx release (e.g. 4 and 5). The timing is quite interesting to have emulated but thats quite hard without really good docs, describing how the VDP is timeslotted.

And I have a very funny bug in a demo I'm working on that I really can't explain. Maybe someone can. The demopart works in all MSX2's and some MSX1's.

I pretty much do this (in screen 1):

1. Wait for VBLANK
2. Change background and foreground color
3. Output some data to the screen
4. Go back to 1.

The time it takes to execute everything is about third of a frame and it works as intended in all MSX2's and some MSX1's. But in some MSX1 machines it looks like the VBLANK bit in SR1 is always set which means that the code totally looses its sync and runs 3 times as fast. The funny thing though is that this happens ONLY when I actually change colors in #2. If I set the background and foreground colors to the same as in previous frame it works fine.

This is really weird I think. I'm reading the new color values from an array and sometimes the new colors are the same as the frame before and sometimes they change. The failed VBLANK sync only happens when the colors actually change.

Any ideas what may be the problem?

Quote:

wasnt color 1 1.1.1?

Yes, indeed. It wasn't