Z86L972 Datasheet, PDF (54/91 Pages) Zilog, Inc. – Low-Voltage Microcontrollers

Z86L972/Z86L973/Z86L974
Low-Voltage Microcontrollers
47
Control and Status Registers
The Z86L972/Z86L973/Z86L974 family has 4 I/O port registers, 33 status and
control registers, and 233 general-purpose RAM registers. The I/O port and con-
trol registers are included in the general-purpose register memory to allow any Z8
instruction to process I/O or control information directly, thus eliminating the
requirement for special I/O or control instructions. The Z8 instruction set permits
direct access to any of these 37 registers. In addition, each of the 233 general-
purpose registers can also function as an accumulator, an address pointer, or an
index register. Registers identified as “Reserved” do not exist or have not been
implemented in this design.
Register Summary
Table 10 through Table 13 summarize the name and location of all registers. The
register-by-register descriptions follow this section.
Table 10. I/O Port Registers (Group 0, Bank 0, Registers 0–F)
Grp/Bnk Reg
(00h) rF
(00h) rE
(00h) rD
(00h) rC
(00h) rB
(00h) rA
(00h) r9
(00h) r8
(00h) r7
(00h) r6
(00h) r5
(00h) r4
(00h) r3
(00h) r2
(00h) r1
(00h) r0
Register Function
General-Purpose RAM Register
General-Purpose RAM Register
General-Purpose RAM Register
General-Purpose RAM Register
General-Purpose RAM Register
General-Purpose RAM Register
General-Purpose RAM Register
General-Purpose RAM Register
Reserved
Port 6 Control Register
Port 5 Control Register
Port 4 Control Register
Reserved
Port 2 Control Register
Reserved
Reserved
Identifier
GPR
GPR
GPR
GPR
GPR
GPR
GPR
GPR
P6
P5
P4
P2
PS010504-1002
PRELIMINARY