I share your excitement regarding the A1000, it is one of my favorite models of Amiga and was my first Amiga also back in 1987. I still have mine, but it needs some work to return it to it's former glory.
There were probably 2 or more different internal RAM expansion boards like what you are referring to. I bought a brand new Spirit Insider to get an additional 1.5mb of fast RAM in my A1000, which was probably the most popular internal RAM expansion board for the A1000. Brings back many fond memories of expanding (spending most of several paychecks back then) my A1000 as far as I could take it. The only thing I could have done more to it would have been a Phoenix replacement motherboard w/030 & 2mb Chip RAM to bring it almost up to A3000 specs, but that was out of my price range at the time.
Enjoy that A1000 and all your own memories of days long past while you are playing with it.
If you are interested in new projects for the A1000 check out the GBA1000's that I and many other members here are building as a DIY project from a small run of new motherboards that were produced last year. Just do a search here to find a few threads about the project.
