Nintendo DMG-01 - Game Boy Console Manual page 33

TM
Game Boy CPU Manual
Resetting of the IF register, which was the cause of
the interrupt, is done by hardware.
During the interrupt, pushing of registers to be used
should be performed by the interrupt routine.
Once the interrupt service is in progress, all the
interrupts will be prohibited. However, if the IME
flag and the IE flag are controlled, a number of
interrupt services can be made possible by nesting.
Return from an interrupt routine can be performed by
either RETI or RET instruction.
The RETI instruction enables interrupts after doing a
return operation.
If a RET is used as the final instruction in an
interrupt routine, interrupts will remain disabled
unless a EI was used in the interrupt routine or is
used at a later time.
acknowledged during opcode fetch period of each
instruction.
by DP
2.12.1. Interrupt Procedure
The interrupt will be
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