I have reserved space in external memory using:

XSEG
ORG 000000h
DMASTART DS 2000
DMASTOP DS 4

so that DMASTART will occupy the first 2000 addresses in external memory and DMASTOP will occupy the next 4. I am running a loop in which I would like DMASTART to pick up right where DMASTOP left off in the previous loop. So DMASTART in the second loop will pick up at the 2004th address and carry through the 6004th address and DMASTOP in the second loop will pick up at the 6004th address and carry through the 2008th address. How do I do this?