Music Module test

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By Grauw

Enlighted (6157)

Grauw's picture

12-08-2017, 02:18

I do for MSX-Music and the SFG-05… I could check for the MSX-AUDIO BIOS, but I’d prefer to detect all devices, not less than I do now… Wink

@Louthrax, on your Philips, if you IN an unused I/O port, what does it return? (Trying to confirm my high-impedance theory.)

By sd_snatcher

Prophet (2567)

sd_snatcher's picture

12-08-2017, 02:11

Maybe one idea could be to try to detect the BIOS first, and only if it's not present fall back to direct I/O.

By Louthrax

Paragon (1638)

Louthrax's picture

12-08-2017, 02:41

sd_snatcher wrote:

Maybe one idea could be to try to detect the BIOS first, and only if it's not present fall back to direct I/O.

Yes, as most of the people do not have any upgraded MSX-AUDIO BIOS (usually no BIOS at all) on their Music Modules... Wondering how the various demos in the 80's were detecting it (and we know they were working on Philips).

Also, do not hesitate to double-check what I said here (I tried on several machines, but some have modified BIOS, some of my Music Modules have been modified too...).

In the hypothesis the Philips BIOSes are modifiying some ports at boot time causing port C0 to return a different value, maybe that could be reverted with some OUTs to C0 & C1, in order to reset the MSX-AUDIO to a default state?

By Grauw

Enlighted (6157)

Grauw's picture

13-08-2017, 02:07

Heh, ok,

1.2.2 System control port setting

“ Bit 2 It is a bit for MSX - AUDIO. If port 0C0H is other than 0FFH, it is judged that MSX - AUDIO exists. ”
“ In this way, judgment of devices other than Kanji ROM is based on the premise that 0FFH will be returned when the MSX bus is pulled up, that is, reading ports that do not exist. ”

Kinda lame, ASCII :D. But I guess if pull-up resistors are mandatory for MSX2, it’ll pass since this is only done in MSX2 and up BIOSes.

By TheKid

Hero (554)

TheKid's picture

15-08-2017, 08:11

If you want to test some more, you can use our Thunderbirds are go promo. After the logo, there is a check to find the music module.
Years ago I addressed the openmsx team, because openmsx didn't detect the music module in this promo. They fixed it, so since then it's detected. If I remember correctly, the real msx used a certain value which it never resetted, where as openmsx did set this value back to a default. After they fixed this, openmsx behaves the same as the real msx 2.

Thunderbirds promo

By Grauw

Enlighted (6157)

Grauw's picture

15-08-2017, 09:34

By TheKid

Hero (554)

TheKid's picture

15-08-2017, 10:01

@Grauw: Yep, that's the one. Wow, 11 years ago.

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