New Online MSX emulator

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By Grauw

Ascended (8612)

Аватар пользователя Grauw

26-04-2016, 19:37

And when I perform the same test in screen 5 (G4) the line width doesn’t change either, indicating that VRAM is getting interleaved so also in G4 the YJK bit seems to override the mode.

By NYYRIKKI

Enlighted (5425)

Аватар пользователя NYYRIKKI

26-04-2016, 19:57

ppeccin wrote:

I know there are emulators like BlueMSX that offer generic machine configs, but where do those ROMs come from?
How were they built?

Can someone shed a light on this?

Only Sony and Panasonic made MSX2+ machines and they were only available for Japanese market. Later many hobbyist have binary patched their own ROMs to have other localisations. The dis-assembly project is also hobby project that is still slowly going on (I think)so it would not surprise me if there was still some errors. How the original ROM's were built is has remained secret of Microsoft, but I have strong feeling they used MS-DOS compatible computer running M80/L80 compiler. At least this is how MSX-DOS was made. (also using 8" floppies Smile ) I think there was also a book where original MSX1 BIOS source code was printed, but don't remember the book name anymore.

By ppeccin

Champion (355)

Аватар пользователя ppeccin

26-04-2016, 20:16

Grauw wrote:

And when I perform the same test in screen 5 (G4) the line width doesn’t change either, indicating that VRAM is getting interleaved so also in G4 the YJK bit seems to override the mode.

Thanks Grauw for testing. Nothing like having a real machine at hand!
Also, very logical observations and conclusions!

Did you test in G5 (Screen 6)? What happens with the border color? Is it still tiled?

Thanks

By Grauw

Ascended (8612)

Аватар пользователя Grauw

26-04-2016, 20:44

Ha! Line width didn’t change, but surprise surprise, the border is still striped. So it’s not actually forcing a mode switch, but rather just a switch in the part which reads the VRAM data, interprets it and outputs pixels.

By mars2000you

Enlighted (5525)

Аватар пользователя mars2000you

26-04-2016, 20:55

Quote:

Only Sony and Panasonic made MSX2+ machines

No, there are also Sanyo MSX2+ machines.

By ppeccin

Champion (355)

Аватар пользователя ppeccin

26-04-2016, 21:19

Grauw wrote:

Ha! Line width didn’t change, but surprise surprise, the border is still striped. So it’s not actually forcing a mode switch, but rather just a switch in the part which reads the VRAM data, interprets it and outputs pixels.

And are the pixels fat or thin?

By Manuel

Ascended (15967)

Аватар пользователя Manuel

26-04-2016, 21:31

Grauw - can you add these test programs to some openMSX ticket, please? Smile

By Grauw

Ascended (8612)

Аватар пользователя Grauw

26-04-2016, 21:44

ppeccin: Actually they were interspersed 4 pixels wide bars, also in screen 5, in screen 7 I got dots. The clear colour was set to 4 btw.

manuel: I used the exact program ppeccin provided, just replaced SCREEN 7 by 5 and 6. I didn’t test in openMSX whether it produces the same result. Ok ok, I’ll create a bug.

Quote:

1 COLOR 15,4,7
10 SCREEN 7
20 LINE (10, 10) - (240, 180) : REM Should take only half the screen width
30 A$ = INPUT$(1)
40 VDP(26) = &h08 : REM Does something change? Is the line still taking half width?
50 A$ = INPUT$(1)

By Manuel

Ascended (15967)

Аватар пользователя Manuel

26-04-2016, 21:50

Thanks mate!

By ppeccin

Champion (355)

Аватар пользователя ppeccin

28-04-2016, 17:13

Grauw, could you make another simple test for me?
I need to know what happens if we set the YJK bit in Screen 0 ~ 4.

That simple basic program will work for Screen 2 ~ 4.

For Screen 0 and 1, you can just type some chars or do a LIST, then execute "VDP(26)=8".
Also for width 80 in Screen 0.

Can you please describe what you see?

Thank you soooo much! Smile

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