ISD_V_VPN
load_addr = ((header[isd+ISD_V_VPN+1]*256 +
header[isd+ISD_V_VPN]) & ISD_M_VPN)
load_addr = (header[isd+ISD_V_VPN+1]*256 +
header[isd+ISD_V_VPN]) * 512;
mopFilePutLX(header, 0xd4 + ISD_V_VPN, dl.loadaddr / 512, 2);