The Bit Wars were an intriguing time in gaming, particularly in the era of one-upmanship between the Super NES and the SEGA Mega Drive / Genesis. While there could be arguments over sound chips, BLAST processing etc, we also saw special enhancement chips produced that'd go within the game cartridges to improve performance or make certain new techniques possible. Individual games could be standard bearers with these enhancements, something we don't see in the modern era.
One example with the SNES was the SA1 chip, which gave boosts in areas like clock speed, faster RAM and more. Perhaps the most famous example of a game using this chip was Super Mario RPG: Legend of the Seven Stars, though the enhancements skipped the PAL territory (Europe / Australia and New Zealand) at the time. Basically, the chip made games run better.
There's been some buzz in the retro community over the weekend as details and footage have been shared of an SA1 Demonstration Program, which runs off an extremely rare cartridge demo board that features the chip. One of the boards made a rare appearance on eBay (where else?) and a kind benefactor with some money to spare picked it up for Vitor Vilela, who creates software and hardware mods and specialises in the SA1 chip. For example they've produced 'SA-1' enhanced versions of some SNES games to show how, theoretically, the chip would have made some classics run with less slowdown and faster loading.
The board's demos have been successfully dumped, giving a look at how Nintendo created a couple of primitive tech showcases to show what the chip could do; you can see them below, but be aware the second half involves a fair bit of nausea-inducing spinning sprites.
If you want a detailed technical breakdown, this Patreon post is well worth a read.
Fascinating stuff, it's certainly an intriguing part of Nintendo's history in the 16-bit era.