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Z86E30/E31/E40
Zilog
Z8 4K OTP Microcontroller
DS97Z8X0500
P R E L I M I N A R Y
35
1
Figure 25. Register Pointer
The upper nibble of the register file address
provided by the register pointer specifies
the active working-register group.
r7
r6
r5
r4
R253
(Register Pointer)
I/O Ports
Specified Working
Register Group
The lower nibble
of the register
file address
provided by the
instruction points
to the specified
register.
r3
r2
r1
r0
Register Group 1
Register Group 0
R15 to R0
Register Group F
R15 to R4*
R3 to R0*
FF
F0
EF
7F
70
6F
60
5F
50
4F
40
3F
2F
30
20
1F
10
0F
00
* Expanded Register Group (0) is selected
in this figure by handling bits D3 to D0 as
"0" in Register R253 (RP).
80
Note: Registers 80H
through EFH are
available in the Z86C30
only.