Z86D990 Datasheet, PDF (59/102 Pages) Zilog, Inc. – Low-Voltage Micro controllers with ADC

Z86D990/Z86D991 OTP and Z86L99X ROM
Low-Voltage Microcontrollers with ADC
52
Control and Status Registers
The Z86D99/Z86L99 family has 4 I/O port registers, 33 status and control regis-
ters, and 233 general-purpose RAM registers. The I/O port and control 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
Analog/Digital Converted Data
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
ADCDATA
P6
P5
P4
P2
PS003807-1002
PRELIMINARY