ZiLOG eZ80 User Manual

eZ80
®
CPU
User Manual
UM007714-0908 Memory Mode Switching
26
The memory mode can be changed by adding a suffix to a CALL, JP, RST, or RET,
RETI, or, RETN instruction. Tables 14 through 20 describe how each of these 4 instruc-
tions function. The individual instructions may perform additional operations that are not
described here. These tables are focused only on the memory mode switching. For more
detailed information, see eZ80
®
CPU Instruction Set Description on page 77.
Table 14. CALL Mmn Instruction
User Code
ADL
Mode
Assembled
Code Operation
CALL mn 0 CALL mn
assembles to
CD nn mm
The starting program counter is {MBASE,
PC[15:0]}. Push the 2-byte return address
PC[15:0] onto the SPS stack. The ADL mode bit
remains cleared to 0. Load 2-byte logical address
{mm, nn} from the instruction into PC[15:0]. The
ending program counter is {MBASE,
PC[15:0]} = {MBASE, mm, nn}.
CALL Mmn 1 CALL Mmn
assembles to
CD nn mm MM
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. Load 3-
byte address {MM, mm, nn} from the instruction
into PC[23:0]. The ending program counter is
PC[23:0] = {MM, mm, nn}.
CALL.IS
mn
0 CALL.SIS mn
assembles to
40 CD nn mm
The starting program counter is {MBASE,
PC[15:0]}. Push the 2-byte logical return address
PC[15:0] onto the {MBASE, SPS} stack. Push a
02h byte onto the SPL stack, indicating a call from
Z80 mode, (because ADL = 0). The ADL mode bit
remains cleared to 0. Load 2-byte logical address
{mm, nn} from the instruction into PC[15:0]. The
ending program counter is {MBASE, PC[15:0]}.
CALL.IS
mn
1 CALL.LIS mn
assembles to
49 CD nn mm
The starting program counter is PC[23:0]. Push the
2 LS bytes of the return address, PC[15:0], onto
the {MBASE, SPS} stack. Push the MS byte of the
return address, PC[23:16], onto the SPL stack.
Push a 03h byte onto the SPL stack, indicating a
call from ADL mode (because ADL = 1). Reset the
ADL mode bit to 0. Load 2-byte logical address
{mm, nn} from the instruction into PC[15:0]. The
ending program counter is {MBASE,
PC[15:0]} = {MBASE, mm, nn}.

ZiLOG eZ80 Specifications

General

Brand	ZiLOG
Model	eZ80
Category	Computer Hardware
Language	English