The NES had a long run, and was still quite popular years after it launched. Yet competition wouldn't stay away forever (and Nintendo's attempts at a monopoly in the United States had been legally struck down), and 16-bit systems were getting in vogue; the Sega Genesis was catching up in the United States, while the PC Engine was gaining ground in Japan.
The Super NES was made to keep up, and so began one of the fiercest Console Wars in history. It was known as the Super Famicom in Japan (officially adopting the "Famicom" nickname of its predecessor, the Family Computer) while in South Korea, it was known as the Super Comboy (슈퍼 컴보이) and it was distributed by Hynix. While the SNES was very much a success (eventually beating out the rival Genesis in market share), Nintendo would still make some mistakes behind the scenes. Nintendo originally had a deal to make a CD add-on for the SNES, and signed with Sony for the latter to make the device. But the contract for the sound chip Sony made included a clause where Sony would receive all software royalties. The President of Nintendo, Hiroshi Yamauchi, decided to drop the contract and sign with Philips midway through development (and behind Sony's back), which turned the relationship into a rocky one. Eventually Nintendo, Sony, and Philips consolidated forces to work on the CD add on, until Sony decided to go it alone, using the already-constructed hardware to launch their own console, the Playstation.
One add-on for the system, did get made: The Super Game Boy, a cartridge attachment that allowed the system to play Game Boy games, and even add color to them.
Also notable for having very different casings on both the console and the games between the American and European versions. The picture shows the American version, with the harder edges, while the Japanese and European editions were more rounded.
Like the NES, the Super NES has a Central Processing Unit for main data processing, and a Picture Processing Unit for the graphics. Also like the NES, the Super NES CPU and PPU have a master clock speed of 21.5 MHz, but the CPU divides it down to between 1.78, 2.68 and 3.58 MHz due to slow (cheap) cartridge ROM, and it was cheaper to make the system with said clock speed. This led to the belief that the SNES was a slow system, and that too much on screen action would slow it down.
The processor itself was a 65C816, a 16-bit successor to the 6502 used in the NES, Apple II, Commodore 64, and Atari consoles and computers. Nintendo actually used Apple IIgs computers as development systems, since they also used the 65C816.
The bus speed was a problem at first, but the system has a lot of memory, and like the NES before, it has a cart-accessible expansion bus, which meant carts could add their own extra processors to run at higher speeds.
One of the most famous of these chips is the "Super FX" chip, a highly specialized 16-bit RISC CPU which was generally used for running Polygonal Graphics. It included some extra RAM for use as a rendering buffer, and for general computing if needed.
Another famous chip called SA-1, used in Kirby Super Star and Super Mario RPG, was a second faster 65C816 clocked at 10.5MHz that was also used for Polygonal Graphics (as well as for Copy Protection).
The most widely used add-on chip was the DSP-1, which was a math coprocessor typically used to speed up 3D calculations in games like Pilotwings and Super Mario Kart. Reportedly, it was originally supposed to be part of the console but was removed at the last minute, catching the Pilotwings developers flatfooted and forcing them to include it in the cartridge, and the rest is history...
The system also has its own sound processor, made by Sony (naturally, this was before Sony made its own system). This wasn't made just to generate sound, but to also mix it, like a MOD with it's own custom instruments/samples , with 8 ADPCM sample-playback channels available. Even though this hardware was advanced, it was bottlenecked by the low amount of space provided by the cartridges and the limited RAM. The filtering hardware managed to remove aliasing in heavily compressed audio samples. However, it also muffled certain types of audio samples. It also did reverb and other sound effects.
Fun fact: this chip allowed volume to be set negative, resulting in phase inversion. Since panning was achieved by setting the left and right volumes of a voice separately, rather than with a dedicated pan control, enterprising developers were able to implement real-time Dolby Surround encoding, which showed up in games like Vortex and Seiken Densetsu 3.
The system has 128 KB of main RAM and 64 KB of Video RAM. That alone gave the Super NES more on-board memory than either of its 16-bit competitors. This doesn't count including extra memory on the carts, as the other systems may have been able to do that as well.
The system also has 64 KB of sound memory. Some games (Final Fantasy VI being an excellent example) loaded up to 10 minutes of music into the sound RAM and played it entirely from there. However 64KBs of RAM was a bottleneck to high quality samples which either had to be compressed heavily or relied on streamed data from the cartridge in order to overcome the RAM limitation. Tales of Phantasia and Star Ocean are known games that used a specialized engine for this.
According to later official documentation, the SA-1 meant ROM chips could utilize up to 8 megabytes (64 Megabits) of read-only memory.
Though any type of bank-switching method could be used to increase memory capacity.
The largest known program for the Super NES is a chip-free hack of Star Ocean that weighs in at 12 MB (96 Mbit). It works on real hardware. The official version used an S-DD1 data decompression chip, allowing it to fit into only 48 Mbit of expensive mask ROM.
The sprites can be as large as 64×64 pixels, with up to 128 on screen, but flickering may still occur if more than 32 sprites are on the same horizontal line (although that's much rarer than on an NES, which allows only 8 sprites of 8 pixels wide, totalling 64 pixels).
The backgrounds can be more complex, with up to four layers of background graphics, although games rarely used that many due to severe color limitations with more than three layers. Or instead of a layered background, games could set the PPU into Mode 7, which was used to achieve the scaling and rotating backgrounds that were part of what set the SNES apart in those days.
The standard resolution is 256×224 pixels. The reason the vertical display is shorter than the NES is that on a typical NTSC television, the extra scanlines would be off the screen anyway, and since the CPU can't send graphics to the PPU while the latter is busy drawing the screen, the system would be wasting precious VRAM update time drawing scanlines nobody would ever see.note The NES did have this problem, but it wasn't as big a deal because the graphics were less complex, and because the PPU relied more on dedicated memory in the cartridge and less on its tiny VRAM. The SNES does have an "overscan" mode that gives it the same resolution as the NES, but developers rarely used it. There were also higher resolutions such as 512×448, but these had limited color depth and were not for sprites; RPM Racing was the only game to use hi-res graphics outside of menus and such.
The total color depth is 15-bit (or 32,768 colors), but everything drawn to the screen can only use 256 of those colors at any one time. Unless you start to mess with transparencies. Or direct-color modes. Or HDMA (the storied "scanline trick")... It is theoretically possible to display all 32,768 colors onscreen at the same time, with certain limits on what colors can appear where.
The system could blend the colors of backgrounds and/or sprites through color addition, subtraction, or averaging, which allowed transparencies to be used, and override the normal on-screen color palette limits.
In short, it exceeded the Sega Genesis in every way in terms of specs save for processing speed and display size.
Stock Control Settings: Was the exemplar of the "cross" button layout (four face buttons shaped like the points on a cross) and the L and R shoulder buttons.
Vindicated by History: The arrival of the 32-bit era wasn't kind to games like Super Metroid, Yoshi's Island, or EarthBound, which were often lost in the shuffle of more technologically advanced games on other systems. However, they would eventually become among the most acclaimed and highly-ranked video games of all time. Super Metroid especially which, nowadays, is often placed on top of lists for the best SNES game ever.