Z87C33 Datasheet, PDF (20/72 Pages) Zilog, Inc. – CMOS Z8® MCU Consumer Controller Processor

Z87C33
CMOS Z8“ MCU Consumer Controller Processor
14
r7 r6 r5 r4
r3 r2 r1 r0
R253
(Register Pointer)
This upper nibble of the register file address
provided by the register pointer specifies
the active working-register group.
FF
F0
Register Group Fh
EF
80
7F
70
6F
60
5F
50
4F
40
3F
Specified Working
30
Register Group
2F
20
1F
Register Group 1
10
0F
Register Group 0
I/O Ports
00
R15 to R0
The lower nibble
of the register
file addresses
provided by the
instruction points
to the specified
register.
R15 to R0
R15 to R4*
R3 to R0*
* Expanded Register File Bank 0 is
selected in this figure by handling bits
D3 to D0 as "0" in Register R253 (RP).
Figure 8.Register Pointer—Detail
General-Purpose Registers (GPR). General-purpose registers are undefined after
the device is powered up. These registers keep the most recent value after any
RESET, as long as the RESET occurs in the V_CC voltage-specified operating
range. General-purpose registers are not guaranteed to keep their most recent
state from a Low-Voltage Protection (V_LV) RESET if V_CC drops below 1.8V.
PS015601-1003