VBE
par->VBE = (upper_margin * 2 + 1); /* must begin on odd halfline */
par->VDB = par->VBE;
unsigned short VRE, VBE, VRS, VDE;
VBE = crdata[12] | ((unsigned short)(sr_data & 0x10) << 4);
temp = VBE - ((E - 1) & 511);