Super Famicom: December 1988
The First Super Famicom Demonstration

The Super Famicom was demonstrated to the Japanese press on November 21, 1988 (precisely 2 years before its proper release), and so Famicom Tsushin Magazine published a special report in their December 23, 1988 issue. The following images were taken from this special report. (I'm sorry about the quality of the pics, but a digital camera is all I've got.) Click on the thumbnails to see some large pictures!
The early SFC in all its glory.
"Finally, an appearance!!"
The SFC is announced before over 200 members of the press. Its capabilities are compared with those of the PC-Engine and Megadrive.
"The SFC is completely incompatible with the Famicom!!"
The page explains how the SFC has no backwards-compatibility with the old Famicom. The SFC will, however, have an A/V input on the back which will accept the A/V signals of the "Famicom Adaptor", the redesigned Famicom with A/V outputs.
"Super Famicom, the ultimate machine!!"
The SFC uses a special multi-out connector for its video, and also the Famicom video when the "Famicom" switch is set to the left.
"The Famicom Adaptor, for Famicom games only!!"
This redesigned Famicom uses the SFC controllers.
Reactions from the Famicom software industry. NEC, Sega, and other developers/makers give their comments(?) on the SFC's introduction.
More reactions, and a prediction from one writer.
"SFC's graphic functions are thoroughly dissected."
Colours and resolutions are discussed, as well as background layers and scrolling capabilities.
Sprite size has been increased, as well as video effects implemented, such as mosaic, fade-in, and fade-out.
Scaling, rotation are shown. "Because it is done by the hardware, it moves fast, fast, fast!!"
A recap of the SFC's graphics power.
"The SFC's sound is also powerful!!"
This page lists the sound capabilities: 8-channel samples, stereo, DSP effects, and clear sound through AV connectors and "VCCI" noise reduction (whatever that is.)
Other hardware capabilities are explained: VCCI (RF noise reduction), H-DMA, ROM addressing.
"Expected types of games you'll be able to play!!"
The Famitsu staff speculate at the types of games the SFC will be able to run, such as those with lots of scaling/rotation, high-quality images, video effects, mathematical caluclations (such as simulations)... that rivals CD-ROM, games that speak and use 8-channel sampled sound, large scale RPGs up to 12 Megabytes, and new types of controllers and control methods.
That's all, folks!
A close up of a (surely addled) Shigeru Miyamoto explaining the SFC hardware.
And here's a close-up of the early controller. Interestingly, the buttons are labeled A,B,C,D (and concave); and the shoulder buttons E and F. A,B are also rotated clockwise 90° from the release version. The E,F shoulder buttons appear far more rounded than in the released controller.

Other interesting things from this report:
The SFC's Work RAM was set at a puny 8 Kilobytes! (To be upped before release, of course.) The sound hardware is said to be "2 Custom LSI chips" Perhaps this meant the sampled audio unit as well as the DSP.
The "Famicom Adaptor" that went unreleased in its current form was still labeled "Family Computer", so it is not by any means an adaptor that sits on top of the SFC.
The legendary picture of a "16-bit Adventure of Link" is shown here. It's likely just a still showing the SFC's graphics tile addressing capabilities, alongside the digitization and colour demonstration still pictures on the same page.

Famicom Hissyoubon Magazine reported on the same demonstration in their Dec. 16 issue:

I've transcribed the first 2.5 pages into text HERE. To get an English translation of the page, click HERE.
The third page contains a 4-page press release by Nintendo. Its text is HERE, and translation is HERE.

To note on this page: Release of the SFC was originally set for July 1989. The Japanese press concentrated most of their reporting on the graphic and sound capabilities of the new machine.
A nice shot across the bow of the machine, plus pics of the sprite & mode 7 demonstrations. What's interesting to note is that 4 games were to be available at launch, including Mario 4 and Zelda 3. Funny how the article also notes that sprite flicker will be a thing of the past...
The four white pages are the press release from Nintendo detailing the machine's specs. I'm surprised nobody noted the SFC's slow clock speed...
Shigeru Miyamoto, no doubt bashfully giving a self-deprecating speech.
The "Famicom Adaptor" (merely a Famicom with A/V out), meant to be the "solution" to playing FC games through the SFC.
The report says that Nintendo was also considering a trade-in program for consumers' old Famicom systems. (This didn't materialize.)
The button naming and spacing are quite a bit different from the release SFC's.
That red & yellow mono A/V pair is actually an AV input from the Famicom Adaptor.
The (now totally retro-looking) headphone jack.
The SFC's sprite demo. Apparently its purpose was to show off large sprites and layers, layers, layers!
This mode 7 demo sure looks awesome, and closer to the final Pilotwings than the 1989 demo of Dragonfly, eh?

Here were the reactions from software companies at the time: (Compare this to their reactions to the NEC SuperGrafx!)
As new media, it is as expected. The performance of the machine seems great, so I want to make games that cannot lose.
It seems to be a high-performance machine. I want to see what kind of software is made.
I think it has advanced functions. It seems to be made for transplants from business-use (arcade?) machines.
Data East
It looks like a good machine. I want to try out Mario 4 and Zelda 3 as soon as possible.
It is the next-generation home video game machine. We'll think hard about how to make use of a 4-button joystick.
I am beyond anticipation. The forecast of 3 million sets sold per year does not seem like a dream. I absolutely want to make something for it.
Although I've heard that it is a great machine, I still can't comment until I've seen the actual thing.
Rotation and scaling functions are good. The abundance of colours is another strong feature.
I took notice of the rotation and scaling functions. It can do more than I had imagined. We're surely starting from 4 Megabit games.
Under influence from the SFC, I expect that the whole game industry will be revitalized.
If the machine as announced will be released at a low price, it will be amazing.
If all the functions of the machine can be mastered, we'll make great software, I think... But games makers will likely be exhausted doing so.
I think that it is a machine with wonderful functions.
I want especially to note the inclusion of rotation and scaling functions.
Toshiba EMI
I took notice of the scrolling functions and sound chip. I wonder whether software will follow. But the price is a problem, isn't it?

Another magazine covered the SFC's anouncement in their February 1989 issue. The article discusses some of the features of the new system (stereo sound, scaling, ROM size, etc...) But the system pictures are intriguing, to say the least! The system on the left side of the page is a redesigned Famicom, called a "Famicom adaptor". This new FC design wasn't produced.

BUT! That picture on the right side of the page shows an early design of the SFC, as above. This time, the labels of the switches are clearly visible: Power Switch; FAMICOM Switch, and Reset Switch! Is this the fabled Super Famicom prototype that was backwards-compatible with Famicom games? Unfortunately, NO. It looks like the SFC was never backwards-compatible with the Famicom after all.