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UM012811-0904
Z8 Compatibility
eZ8 CPU
User Manual
11
Alternate Function Opcode
To accommodate the new instructions, the opcode
1FH
refers to a new second opcode
map. The
1FH
is pre-pended to an opcode to select the alternate functions available on the
second opcode map. The CPC, CPCX, SRL, LDWX and PUSH (immediate) instructions
use this second opcode map. Users writing assembly language code can employ the CPC,
CPCX, SRL, LDWX and PUSH (immediate) instructions directly. The eZ8 CPU assem-
bler automatically inserts the
1FH
opcode as necessary.
Moved Instructions
Some of the existing Z8
®
CPU instructions have been moved to new opcodes in the eZ8
CPU. Table 5 lists these moved instruction.
Removed Instructions
The instruction types LD r1, R2 and LD R1, r2 have been removed from the opcode map
as they are now subsets of the LD instruction (opcode E4) using Escaped mode address-
ing. In the Z8
®
CPU, these instructions used opcodes
08H
through
F8H
and
09H
through
F9H
. The assembler for the eZ8 CPU continues to support these instructions. Refer to the
Address Modes chapter and the LD instruction description for more information.
The WDH (Watch-Dog Timer Enable During HALT Mode) instruction has also been
removed. For information regarding the Watch-Dog Timer, refer to the Product Specifica-
tion for the specific device.
TCMX
Test Complement Under Mask using Extended Addressing
TMX
Test Under Mask using Extended Addressing
XORX
Logical XOR using Extended Addressing
Table 5. Instructions with New Opcodes
Instruction
eZ8 CPU Opcode (Hex)
Z8
®
CPU Opcode (Hex)
SRP
01
31
DEC R1
30
00
DEC IR1
31
01
JP IRR1
C4
30
NOP
0F
FF
Table 4. New Extended Addressing Instructions (Continued)
Mnemonic
Instruction Description