MASK4            1959 src/dps8/dps8_cpu.h      cpu.PAR[n].AR_BITNO = (b % 9) & MASK4;
MASK4            1965 src/dps8/dps8_cpu.h      cpu.PAR[n].AR_BITNO = b & MASK4;
MASK4             226 src/dps8/dps8_eis.c     c &= MASK4;
MASK4            2311 src/dps8/dps8_eis.c 
MASK4            2416 src/dps8/dps8_eis.c                                     (- (bits % 9)) & MASK4);
MASK4            2425 src/dps8/dps8_eis.c                                     (- (r % 9)) & MASK4);
MASK4            2260 src/dps8/dps8_fnp2_iomcmd.c                     word4 modem_type = (subch_data >> 9)  & MASK4;
MASK4            2264 src/dps8/dps8_fnp2_iomcmd.c                     word4 dev_speed = subch_data  & MASK4;