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Exploring Colecovision screen modes


Serguei2

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I spent all the day if I can use all screen modes on Colecovision

Modes 1 and 2 are easy.


But I can't get screen o and 3.


Mode 0:

Reg/Bit 7 6 5 4 3 2 1 0
0 - - - - - - M2 EXTVID
1 4/16K BL IE M1 M3 - SI MAG


0 0 0 0 0 0 0 0
1 0 1 0 0 0 0 0

vdp_out(0,0);
vdp_out(0,0xA0);

I disabled BL because screen 0 has no sprites anyway.
This code doesn't work


Mode 3


Reg/Bit 7 6 5 4 3 2 1 0
0 - - - - - - M2 EXTVID
1 4/16K BL IE M1 M3 - SI MAG

0 0 0 0 0 0 0 0
1 1 1 0 1 0 0 0


vdp_out(0,0);
vdp_out(0,0xE8);


This code doesn't work either


I expect the letters in mode 0 would be smaller

And mode 3, sprites would be look with big pixels.


I will stick with mode 2 since, the characters are big enough and the sprites are just fine.

2 Comments


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Text mode, letters would be more crunched together that it is drawing 6 pixels across per tiles.

 

I think you mean to use vdp_out(1,0xE8);

 

And then set up the register 2-7 to assign pattern table which would be vdp_out(4,0) to tell it it is at vram address 0x0000. And then the name table vdp_out(2,6) to assign the name table to vram address 0x1800. Then assign text color and backdrop color to register 7 vdp_out(7,0xf2) which the text will be white with bright green background. You might be able to use getput library in this mode like print_at(1,1,"HELLO);. There's no color table or sprite table in this mode.

 

page 2.4.4 in the tms9918.pdf book have information on text mode.

 

I haven't played with multicolor mode before. testscr2 is an example that came with newcoleco homebrew kit that uses multicolor mode.

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Thanks for the advice, Kiwi. Now, I can use all the screen modes.

 

I noted in mode 3 (multicolor mode), the text is scrambled but the sprites still work.

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