X-CALIBUR is a 128 Mb expansion / acceleration RAM unit for the Amiga 4000 / 040.

Let us explain what we mean by that! It is a 128 Mb memory expansion because it allows you to add up to 128 Mb of fast RAM to your A4000 / 040 (not 030, sorry).

How can it accelerate at 25 MHz without changing the CPU at all? And not even your current memory?

Well first the X-CALIBUR uses 64 bits interleaved memory instead of regular 32 bits access, this is why we need to populate modules 2 at a time, in using two memory banks separated by half a clock we in fact cut the access
time in half, resulting in double speed memory. The second thing is that the A4000 motherboard does not allow memory bursting, but our board does, so we again double our memory speed; in total we then have quadruple our
memory speed at 25 MHz!!! And 5.4 times faster at 33MHz!!!