I bought one on eBay, and it's a quirky device. It's essentially a glorified floppy drive with proprietary disks, and it makes loud, albeit amusing scanning noises.
Every Nintendo console prior to the Wii had some sort of "expansion" or upgrade capability for future peripherals to be added. Hardware revisions took the place of this model.
Plus, adding more texture memory would have meant respinning the RCP silicon. That would have been a significant expense for marginal returns.
Besides, Nintendo had already sold a memory upgrade in the form of the Expansion Pak. A second memory upgrade which couldn't even be installed into existing consoles would have been a very difficult sell, and could have soured customers on their future consoles. ("Why buy a Game Cube when they'll just release a Game Cube Plus next year?")
the https://en.wikipedia.org/wiki/Nintendo_64_accessories#Expans... raised main memory from 4mb to 8mb.
it was required for one of the Zelda games, but also helped with graphics for some games if it was inserted.
seemed to be a decent success.
https://www.reddit.com/r/n64/comments/ft63zn/dk64_memory_lea...
The lead artist claims they’d always been planning to make use of it. There’s compelling evidence of a memory leak or similar issue since the released version of the game apparently crashes if you leave it running for some amount of time over 10 hours (which wasn’t usually a problem in practice except for very long speedruns until it was released on Wii U Virtual Console and people started using save states which don’t reset the timer the same way as turning the game off and on does).
I _think_ it was on the documentary clips shipped with Rare Replay, but I'm not 100% on that.