I don't believe that...........if this were True, how is it that an A500 wich was created before 2mb CHipRAM existed is able to see the 2mb ChipRAM from a MegaCHIP add-on without changing any of the customs chips?
Those expansions did change custom chips - they swapped the old 512K or 1MB Agnus with the then-new 2MB version that had been built for A3000s, A600s, and A500+s.
In the case of the 4000, at the *very least* the 2MB Alice would have to be replaced with an 8MB Alice (which does not exist).
