RTW_SCR
PRINTREG8(regs, RTW_SCR);
scr = RTW_READ8(regs, RTW_SCR);
RTW_WBW(regs, RTW_PSR, RTW_SCR);
RTW_WRITE8(regs, RTW_SCR, scr);
RTW_SYNC(regs, RTW_SCR, RTW_SCR);