HMS87C1304A Datasheet, PDF (18/70 Pages) Hynix Semiconductor – CMOS SINGLE-CHIP 8-BIT MICROCONTROLLER

HMS87C1304A/HMS87C1302A
HYUNDAI MicroElectronics
PSW
NEGATIVE FLAG
OVERFLOW FLAG
BRK FLAG
MSB
LSB
N V - B H I Z C RESET VALUE: 00_H
CARRY FLAG RECEIVES
CARRY OUT
ZERO FLAG
INTERRUPT ENABLE FLAG
HALF CARRY FLAG RECEIVES
CARRY OUT FROM BIT 1 OF
ADDITION OPERLANDS
Figure 8-3 PSW (Program Status Word) Register
[Interrupt disable flag I]
dress.
This flag enables/disables all interrupts except interrupt
caused by Reset or software BRK instruction. All inter-
rupts are disabled when cleared to “0”. This flag immedi-
y _{ately becomes “0” when an interrupt is served. It is set by}
r _{the EI instruction and cleared by the DI instruction.}
a _{[Half carry flag H]}
in ^{After operation, this is set when there is a carry from bit 3}
of ALU or there is no borrow from bit 4 of ALU. This bit
can not be set or cleared except CLRV instruction with
lim ^{Overflow flag (V).}
[Break flag B]
e _{This flag is set by software BRK instruction to distinguish}
Pr ^{BRK from TCALL instruction with the same vector ad-}
[Overflow flag V]
This flag is set to “1” when an overflow occurs as the result
of an arithmetic operation involving signs. An overflow
occurs when the result of an addition or subtraction ex-
ceeds +127(7F_H) or -128(80_H). The CLRV instruction
clears the overflow flag. There is no set instruction. When
the BIT instruction is executed, bit 6 of memory is copied
to this flag.
[Negative flag N]
This flag is set to match the sign bit (bit 7) status of the re-
sult of a data or arithmetic operation. When the BIT in-
struction is executed, bit 7 of memory is copied to this flag.
18
Preliminary
Jan. 2001