Ahh, okay. I saw it on ebay and thought this was some kind of bundle pak. Too bad the games didn't support rumble and save simultaneously. Thought the switch was to control the amount of rumble.
Thanks for the clarification of this pak.
I have two combination paks; one is a battery powered unbranded pak with one memory bank and a rumble feature (I think it's unbranded, all it says on it is "WF Attitude"), and the other is a Gamester branded pak that doesn't use batteries (presumably it's EPROM based), with four memory banks and a rumble feature. On both, you can only have the rumble OR gamesave ability at any one time, the N64 cannot access both the rumble pack feature AND the memory bank simultaneously - both units have a switch on them that lets you choose whether the pak is at that time to function as a rumble pak or as a gamesave unit.
The Gamester unit has four memory banks, but you can only access one of the four at any one time (you choose which to use via it's inbuilt switch). I assume this is because the N64 is hardwired to only accept gamesave memory banks of one size (is it 128KB?), so the only way to have four times as much gamesave memory is to have four individual gamesave memory banks and make sure the N64 can only access one gamesave memory bank at any one time. The disadvatanges are of course that not only do you not know which memory bank has the gamesave you want at that time, so you have to cycle through the four until you find it, but also that if, for example, you need eight code pages to save a game, but none of the memory banks has eight pages free (even if together the number of free pages on the four memory banks totals way above eight) then you can't save on the pak.
Having four seperate memory banks is much better than just one of course, but it's a real pity that it's not one memory bank that's four times the size of the N64 standard memory bank.