The Earliest A2000's were not REV 4.x Motherboards those were B2000. The First A2000 were limited release and not expandable. CBM Canada had a trade up deal for anyone with the Early revisions. There units were manufactured in Germany and didn't have the CPU expansion slot, and used the same Agnus as the A1000 the 40 Pin Package not the Fat Agnus Package and were therefore limited to 512K of Chip Ram.
