@PhatBoiCollier:
You missed the point :-)
The first half meg was CHIP mem, the second half was SLOW mem (neither chip nor fast) accessed through the same timing on the motherboard, but outside the rather low address window the graphics and sound chips could DMA to. Cutting a trace in a jumper near the CPU and soldering in a small wire, so that two address lines from the CPU to Agnus swapped places, moved the SLOW mem into the CHIP mem range (late A500 motherboards with proper Agnus version only). I had 1M chip and 2M fast in my A500. Wasn't half bad then.