Z87100 Datasheet, PDF (16/48 Pages) Zilog, Inc. – Wireless Transmitter

Z87100
Wireless Transmitter
Zilog
FUNCTIONAL DESCRIPTION (Continued)
R253 RP
D7 D6 D5 D4 D3 D2 D1 D0
Expanded Register File Pointer
Working Register Pointer
Figure 12. Register Pointer
Register File. The Register File consists of two I/O port
registers, 124 general-purpose registers, 15 control and
status registers, and ten system configuration registers in
the Expanded Register Group, including six registers in
support of the PN modulator. The instructions can access
registers directly or indirectly through an 8-bit address
field, allowing use of a short 4-bit register address with the
Register Pointer. In the 4-bit mode, the Register File is di-
vided into 16 working register groups, each occupying 16
continuous locations. The Register Pointer addresses the
starting location of the active working-register group.
Caution: D4 of Control Register P01M (R248) must be
0. If the Z87100 is emulated by Z86C90, D4 of P01M
has to change to 0 before submission to ROM code.
GPR. The Z87100 has one extra general-purpose register
located at %FE(R254).
r7 r6 r5 r4
r3 r2 r1 r0
R253 (%FD)
(Register Pointer)
The upper nibble of the register file address
provided by the register pointer specifies
the active working-register group.
7F
Register Group F
70
•
•
•
•
•
•
•
•
R127 to R111
•
•
•
•
•
Specified Working
•
Register Group
2F
20
1F
Register Group 1
10
0F
Register Group 0
I/O Ports
00
The lower nibble
of the register
file address
provided by the
instruction points
to the specified
register.
R31 to R16
R15 to R4
R3 to R0
Figure 13. Register Pointer
3-16
PRELIMINARY
DS96WRL0700