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Zilog EZ80F916 User Manual

Page 48

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eZ80

®

CPU

User Manual

UM007715-0415

Interrupts

39

Table 22. Interrupt Mode 0 Operation

Current
Memory Mode

ADL
Mode
Bit

MADL
Control
Bit

Operation (if RST n or CALL Mmn is placed on the
data bus)

Z80 mode

0

0

Read the RST n of CALL mn instruction placed on the

data bus, D[7:0], by the interrupting peripheral.
IEF1

0

IEF2

0

The starting program counter is {MBASE, PC[15:0]}.

Push the 2-byte return address, PC[15:0], onto the

{MBASE,SPS} stack. The ADL mode bit remains

cleared to 0. Write {00h, nn} or {mm, nn} to PC[15:0].

The ending program counter is {MBASE,

PC[15:0]} = {MBASE, 00h, nn} or {MBASE, mm, nn}.

The interrupt service routine must end with RETI.

ADL mode

1

0

Read RST n or CALL Mmn instruction placed on the

data bus, D[7:0], by the interrupting peripheral.
IEF1

0

IEF2

0

The starting program counter is PC[23:0]. Push the 3-

byte return address, PC[23:0], onto the SPL stack. The

ADL mode bit remains set to 1. Write {0000h, nn} or

{MM, mm, nn} to PC[23:0]. The ending program

counter is PC[23:0] = {0000h, nn} or {MM, mm, nn}.

The interrupt service routine must end with RETI.

Z80 mode

0

1

Read RST n or CALL Mmn instruction placed on the

data bus, D[7:0], by interrupting peripheral.
IEF1

0

IEF2

0

The starting program counter is {MBASE, PC[15:0]}.

Push the 2-byte return address, PC[15:0], onto the

SPL stack. Push a 02h byte onto the SPL stack,

indicating interrupting from Z80 mode (because

ADL = 0). Set the ADL mode bit to 1. Write {0000h, nn}

or {MM, mm, nn} to PC[23:0]. The ending program

counter is PC[23:0] = {0000h, nn} or {MM, mm, nn}.

The interrupt service routine must end with RETI.L

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