Z87233 Datasheet, PDF (19/71 Pages) Zilog, Inc. – CMOS Z8-R MCU Consumer Controller Processor

Z87233
CMOS Z8“ MCU Consumer Controller Processor
13
Working Register File. The Z8 standard register file (Bank 0) contains 3 I/O port
registers, 237 general-purpose registers, and 15 control and status registers.
Expanded register file Bank Fh contains 4 system-configuration registers. The
working registers are accessed directly or indirectly via an 8-bit address field. As a
result, a short 4-bit register address can use the Register Pointer (Table 5 and
Figure 9). In the 4-bit mode, the working register file is divided into 16 working reg-
ister groups, each occupying 16 continuous locations. The Register Pointer
addresses the starting location of the active working register group.
Throughout this document, Bank 0 is referred to as the Z8 Standard Register File.
Table 4. Register Pointer Register—RP FDh/R253 Bank 0h: READ/WRITE
Bit
D7 D6 D5
R/W
R/W R/W R/W
Reset
0
0
0
Note: R = Read, W = Write, X = Indeterminate.
D4
R/W
0
D3
R/W
0
D2
D1
D0
R/W R/W R/W
0
0
0
Bit
Position
D7–D4
Bit
Field
Working Registers
D3–D0 ERF
Reset
R/W State Description
R/W
0 Working Register Group
Pointer
R/W
0 Expanded Register File
Expanded Register File (ERF). The Z8 register file is expanded to allow for addi-
tional system control registers, and for mapping of additional peripheral devices,
along with the I/O ports, into the register address area. The Z8 register address
space 0 through 255 is implemented as 16 groups of 16 registers per bank (Fig-
ures 8 and 9 ). There are 16 banks known as the Expanded Register File (ERF).
Bits 7–4 of register RP select the Working Register Group. Bits 3–0 of register RP
select the Expanded Register File Bank. Four system configuration registers
reside in the Expanded Register File at Bank Fh—PCON, SMR, SMR2, and
WDTMR. The remainder of the Expanded Register is not physically implemented,
and is open for future expansion.
PS022701-0104