texas instruments 9918 and 9928 video modes

This is a video I made to briefly talks about the video modes we can use when programming games for ColecoVision but also for other systems like the ti99/4a, sg1000 and msx1 to name only these machines.

I used the AT&T text-to-speech democore web page to add voice rather than plain text everywhere. A machine talking about computer graphics...

If you want to help translating this video to other languages or accept to do voice acting for free, don't hesitate to leave me a message.

thanks for watching

Category:

Entertainment

Tags:

• texas
• instruments
• 9918
• 9918a
• 9928
• 9928a
• graphic
• video
• modes
• coleco
• colecovision
• ti99/4a
• sg1000
• msx1

[fcycles]

could you split horizontaly a screen with 2 mode? If then, what happen to the sprites?

[newcoleco]

I think no one tried to split a screen with 2 different modes.

Each mode is represented by a flag (1 bit), except one which is the mode by default when there is no flag set at all. By setting more than one mode flag, we can mix them and get strange modes that can be used in theory.

In SmartBasic, a low-graphic mode with big pixels is simulated instead of being used, giving the impression of a screen splited : one part with big pixels, and the other part for text.

[fcycles]

Do you have a flag for hsync? if so, it's stable or I guess it could delay of few clock? The very low res mode seem interesting, maybe a very simple 3d engine could be build with it? ;-)

[newcoleco]

Well, I did think of using a kind of ray-tracing engine with a precalculated values table to be nicely used with the low res mode... but like many homebrew projects, I can't find spare time to try.

Updating the video RAM or the video control registers during the retrace of the screen can corrupt the video rendering. So, in a sense, I suppose you can ask for a different mode in the middle of the retrace but will it happends? I don't know, but I presume it will simply corrupts the display.

[kjlg74]

My first home computer was a TI99/4a, and I loved it! I remember programming sprites and other graphics in TI-BASIC many many many years ago. Ahhh... memories!! :)

[fcycles]

I do understand (lack of spare time). It's amazing everything you manage to do over the time. Congratulation, keep up the good work!

[jankoji8]

Wow...I just figured out HOW to program GRAPHICS W/ SPRITES and WITHOUT!

Cool!