Eddie's right - UK cars with chipped keys started with the Series II cars in '96. As for Mk1 JDM cars (i.e. all Eunos Roadsters), I don't think they ever got a chipped key. My '96 Eunos certainly doesn't and it still has all its original keys.
As for wintering the car if you're planning to SORN it, for the last 3 winters I've used a Car Jacket (
www.carbag.com) and it's been brilliant. Car comes out each spring as good as the day I put it away - even the brake discs are shiny without a hint of surface rust. The only down side is you need a garage (doesn't need to be dry one though, nor do you need power) and of course you can't really tinker with the car during those dark winter months without opening it all up again - worth having a second hobby (or a job)... It wasn't the cheapest thing to buy (about £280 landed in the UK) but it's already paid for itself in terms of saving me heating/dehumidifying my garage, or dealing with rust.
Cheers,
Brad.