GMS81508B HYNIX [Hynix Semiconductor], GMS81508B Datasheet - Page 22

• Manufacturer Part Number: GMS81508B
• Description: HYUNDAI MICRO ELECTRONICS 8-BIT SINGLE-CHIP MICROCONTROLLERS
• Manufacturer: HYNIX [Hynix Semiconductor]

HYUNDAI MicroElectronics
[Zero flag Z]
This flag is set when the result of an arithmetic operation
[Interrupt disable flag I]
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-
ately becomes “0” when an interrupt is served. It is set by
the EI instruction and cleared by the DI instruction.
[Half carry flag H]
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
Overflow flag (V).
[Break flag B]
This flag is set by software BRK instruction to distinguish
BRK from TCALL instruction with the same vector ad-
dress.
[Direct page flag G]
DEC. 1999 Ver 1.04
when G=1, page is selected to “page 1”
SELECT DIRECT PAGE
OVERFLOW FLAG
NEGATIVE FLAG
Figure 8-3 PSW (Program Status Word) Register
BRK FLAG
PSW
MSB
N
V G B H
or data transfer is “0” and is cleared by any other result.
This flag assigns RAM page for direct addressing mode. In
the direct addressing mode, addressing area is from zero
page 00
addressing area is assigned 100
SETG instruction and cleared by CLRG.
[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
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.
I
Z C
LSB
H
RESET VALUE: 00
to 0FF
H
CARRY FLAG RECEIVES
CARRY OUT
ZERO FLAG
INTERRUPT ENABLE FLAG
HALF CARRY FLAG RECEIVES
CARRY OUT FROM BIT 1 OF
ADDITION OPERLANDS
H
) or -128(80
when this flag is "0". If it is set to "1",
H
H
GMS81508B/16B/24B
). The CLRV instruction
H
to 1FF
H
. It is set by
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