You can add 8 MB of ZorroII RAM, but the space is shared with the GFX gard, so Spectrum leaves 6 MB available. It may act as safety margin if you somehow fill the accelerator RAM totally - and you see the machine to crawl with the max 3.5 MB/s ZorroII speed. Done it with my A500T/060/128MB Blizzard RAM + 4 MB Oktagon ZorroII RAM just to see the slowness...
