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 the Sega Genesis was catching up in the United States, while the TurboGrafx-16 was gaining ground in Japan.
The SNES 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's 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 European edition was more rounded.
Like the NES, the Super NES has a CPU 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, which was basically a GPU for running Polygonal Graphics. It even had some extra memory.
Another famous chip called SA-1, used in Kirby Super Star and Super Mario RPG, was a second faster 65C816 clocked at 10.5 MHz that was also used for Polygonal Graphics (as well as for Copy Protection).
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.
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.
The ROM size could range from 512 KB (most of the launch games) to 6 MB (Star Ocean 1 and Tales of Phantasia). Keep in mind that these were advertised by their bit size, not their byte size, so they would be listed as 4 megabits to 48 megabits.
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 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 spites 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 CPU 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 NTSC screens would just display 224 vertical lines for the NES anyway, giving the CPU more time to send graphics to the PPU. Some games had the ability to use higher resolutions such as 512x448.
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.
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.