MASK BIT Flag NAME
0x0001 0 CF Carry flag S
0x0002 1 1 Reserved
0x0004 2 PF Parity flag S
0x0008 3 0 Reserved
0x0010 4 AF Adjust flag S
0x0020 5 0 Reserved
0x0040 6 ZF Zero flag S
0x0080 7 SF Sign flag S
0x0100 8 TF Trap flag (single step) X
0x0200 9 IF Interrupt enable flag C
0x0400 10 DF Direction flag C
0x0800 11 OF Overflow flag S
0x1000 12,13 1,1 I/O privilege level (286+ only) always 1 on 8086 and 186
0x2000 14 1 Nested task flag (286+ only) always 1 on 8086 and 186
0x4000 15 1 on 8086 and 186, should be 0 above Reserved