NES tape drive??? Need tech info!

[davidbrit2]

Anybody think it might be as simple as hooking up a tape recorder to the audio-out on the side of the system? Really. To save, you hit record on the recorder and then hit save in the game. To load, hit load in the game and then play the recording.

I'm hoping that it really is that simple. But we'd first need to figure out which pins on the expansion port handle audio input and output.

[Great Hierophant]

Mach Rider, Wrecking Crew and Excitebike were all released long before the Famicom Disk System's release. Moreover, Famicom Disk System versions of Excitebike and Wrecking Crew were released years after the Famicom Disk System's debut.

First, there was a Tape Drive for the Famicom, usually paired with the Family Basic Keyboard and BASIC cartridge. Obviously, the Tape Drive was used to save BASIC programs. I believe that the the Keyboard connected to the Famicom Expansion Port and the Tape Drive connected to the pass-through connector on the Family Basic Keyboard. However, they were sold separately and from emulator tests I believe it could be made to work with a real NES.

Now, we should feel lucky that Nintendo decided not to change the ROMs they used for these particular games. The Japanese and American cartridges use the exact same ROM chips. In the Excitebike manual, it states: "Save and Load functions are not operable in this game; they have been programmed in for potential product developments." I guess they had planned to release the Tape Drive but failed to do so for whatever reason.

Thus the Tape Drive questions become two: First, will any tape recorder work, or must the tape recorder be a Nintendo part? Second, how do you connect a tape recorder to the NES Expansion Port? My initial reading of the paltry documents available suggest that hooking up the outputs to the inputs and vice versa won't work because the data is encoded in binary, requiring a digital square wave signal, not an analog audio signal.

You may find the answers, including pinouts of the NES and Famicom Expansion Ports, here:
http://nesdev.parodius.com/

[GarrettCRW]

Just as a note to everyone: the Programmable Series was released in Japan as cartridges-in 1984 (two years before the FDS arrived). I've seen nothing that implies that the Famicom versions had any real functionality to the save option, either.

[Great Hierophant]

I have discovered further information. First, the Famicom Expansion Port has an Audio Output pin, but no Audio Input pin. The Famicom, if it sends out a signal as described above, must send it out on the audio output pin for recording/saving to the Cassette Player. Now, to load/playback data, the Audio Output of the Cassette Player is connected to the $4016 D0 pin on the Expansion port. (I'm not sure if more is involved, but the data should still be in a binary square wave format suitable for proper reading by the I/O port.)

As for pressing play and record, here is what should happen. For loading, press start at Load, then press play on the tape when you see Loading. For saving, the best practice seems to be to press Record, then press start at Save. Also, during saving and loading, I would not touch the controller #1 in any way other than to start the action.

The Save/Load functions work in the VirtuaNES emulator.

[davidbrit2]

Hmm, very very interesting! This is one of those times where I really wish I had an oscilloscope. ;-) That's a bit troublesome if it uses a square wave encoding, but there's probably some way around that.