NEC UPD789026 Series User Manual page 156

(4) Program status word (PSW)
The program status word is a register used to hold the instruction execution result and the current status of
the interrupt requests. The IE flag to set maskable interrupt enable/disable is mapped.
Besides 8-bit unit read/write, this register can carry out operations with a bit manipulation instruction and
dedicated instructions (EI and DI).
automatically saved into a stack, and the IE flag is reset to 0. It is restored from the stack with the RETI and
POP PSW instructions.
RESET input sets PSW to 02H.
7 6
Symbol
PSW IE Z
IE
0 Disable
Enable
1
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156
CHAPTER 10 INTERRUPT FUNCTIONS
When a vectored interrupt request is acknowledged, PSW is
Figure 10-5. Program Status Word Configuration
5 4 3 2 1
0 AC 0 0 1
Interrupt Acknowledge Enable/Disable
User's Manual U11919EJ3V0UM00
After Reset
0
02H
CY
Used when normal instruction is executed