Revive the Joystick 2 MIC functionality on NOAC, possible?

We all know that some games require the MIC functionality. But it is not available on AV Famicom nor on NOAC Famicom clones.
According to this schematic,
The MIC signal has two paths:
The analog signal is sent and mixed with the audio output, so that we can hear the voice we speak to the MIC from the audio output. Reviving this part of circuit can be easily achieved.
The digital signal is sent to a Three-state Hex Reverter, controlled by /INP0 (named as /OE1 on wiki) of CPU, and then D2 of CPU. Reviving this part of circuit is also not difficult on AV Famicom since we can get all we want.
But it is not possible to get the /OE1 of CPU on an NOAC. So the signal can not be controlled.

Anybody has any ideas?

How is NOAC sending clock pulses to the controller? Does the low-level mode of allpads show that $4016 D2 is open bus, or is it driven low?

Sounds a good idea! I'll try this and see if it works. Thank you very much!

In two different famiclones that I've fixed there was problem with non-working joypad.
What I did was to add special CPLD board which decodes $4016/$4017 access into generatng strobe/clock signal and puttind the data bit from joypad connector into cartridge data bus.

It worked, so if you put data bits onto data bus when accessing $4016/$4017, NOC's CPU will read them.

Do NOAC systems have parallel controller inputs, serializing them internally?

Your allpads is mapper0?
However there is no CHR in the ROM.

This and RHDE: Furniture Fight use mapper 0 + CHR RAM. If you can't modify an NROM board to use CHR RAM, you could run it on any UxROM, BxROM, or AxROM board.

I finally modified a UNROM board to flash cart successfully and burned allpads on it.

$4016 D2 on my NOAC is driven low, not open bus.



A little surprise is that both $4016 D7 and &4017 D7 are driven low!

If you're lucky, your NOAC actually has a physical package (and isn't just an epoxy blob). Then you'd be able to figure out which pin corresponds to the microphone.

If you're unlucky, there's just a black blob of epoxy covering the die. That's basically out of the scope for fixing unless you have a friend with a wire bonding machine.

By searching something completely unrelated I ended up on a site (in Japanese) that talks how an AV famicom was modified to add the mic back.

http://vaot.mydns.jp/fc/nfau.htm

Maybe this information could be useful since there are some schematics and images on how to do it. An original controller was converted too.

QFP package of NOAC is rare nowdays. Most of them are black blob of epoxy. Mine too...