Hello everyone,
Can anyone tell me what the rear port was designed for on the FDS Cartridge? (The one on the back with sliding cover)
Thanks.
It's an expansion port but I believe it officially remained unused.
It contains 6 I/O pins and I think you could also output expansion sound through it, but I can't find any info about that on the Nesdev wiki so I might be misremembering.
Quote from: P on June 28, 2023, 02:43:22 pmIt's an expansion port but I believe it officially remained unused.
It contains 6 I/O pins and I think you could also output expansion sound through it, but I can't find any info about that on the Nesdev wiki so I might be misremembering.
Thanks :-)
Apparently audio comes out of one of the pins, according to ImATrackMan:
More info here: https://www.famicomworld.com/forum/index.php?topic=12002.msg162415#msg162415
Oh thanks for bringing that old thread up. :)
So it seems it's not just the expansion audio, it outputs the fully mixed APU + RP2C33 expansion audio along with the general I/O. And Nintendo seems to have reused the connector for the French NES' RGB output (they converted PAL to RGB only because it was cheaper than making a dedicated SECAM NES, and French TV-sets had RGB SCART by this point).
We still need a pinout though. Judging by ImATrackMan's picture the audio output pin is one of the outermost pins. One of the pins should be GND and another is probably +5 V, then there should be the 6 I/O pins leaving only one unknown pin out of the 10. Could it be battery status perhaps?
I guess I could whip together a test program, run the disk image via FDSStick and probe the pins someday...