I haven't done the mod for the SK1 (only on the SK8), but the sk1 memory upgrade, as far as I understand, would behave similarly to an SK8 that doesn't have batteries in it. That is, when you switch it off, with no batteries installed, and then switch it back on again, the processor would behave like an SK1 and think that there is no samples stored in RAM, even if there is (the processor has a small RAM memory to tell it where to find things) .
To get the SK8 and SK1 to "find" the samples previously stored, a memory protect switch is connected to the RAM chip (to its "write enable" pin) and put in the protect position, and a fake sample record is done, by speaking into the microphone after hitting the sampling button. When it finishes the "sampling", instead of hearing what you just spoke in the microphone, you will hear the sample that you originally saved to the RAM.
The sequencer data is also stored in the sample RAM, so it will also retain it, but "forget" where it is - you just do the same thing as the sample trick - set memory switch to "protect", record a quick random sequence. When you hit play, your proper, previously recorded sequence will come out instead.
What will be lost each time will be the envelope you had on the sample, so you'll have to choose the envelope for the sample again. Also any sounds made using the synthesis section will be lost. Both of these memories are stored in the processor RAM, so they won't be saved by the memory upgrade.
Check out the 32x memory expansion and other SK5/SK8 mods here:
http://www.jz-server.de/forum2/e107_plugins/forum/forum_viewtopic.php?125and a simple 2x memory expansion for the SK5/SK8 here:
http://www.jz-server.de/forum2/e107_plugins/forum/forum_viewtopic.php?22- bear in mind that although these expansions are for the SK5 and 8, you can adapt them easily by the same principles to the SK1 (except that you'll need 2 RAM chips for the upgrade because the SK1 has 2 RAM chips, as opposed to the SK5/8, which have only 1)
Cheers, Graham