Z86C61 Datasheet, PDF (20/46 Pages) Zilog, Inc. – CMOS Z8 MICROCONTROLLER

FUNCTIONAL DESCRIPTION (Continued)
Z86C61/62/96
Z8^® MICROCONTROLLER
Register File. The Register File consists of four I/O port
registers, 236 general-purpose registers and 16 control
and status registers (Figure 18). There are eight further
registers for I/O ports 4, 5 and 6 in the Expanded Register
File (Bank F, R9-R2) (Figure 20).
The instructions can access registers directly or indirectly
through an 8-bit address field. The Z86C61/62/96 also
allows short 4-bit register addressing using the Register
Pointer (Figure 19). In the 4-bit mode, the Register File is
divided into 16 working register groups, each occupying
16 continuous locations. The Register Pointer addresses
the starting location of the active working-register group.
Note: Register Bank E0-EF can only be accessed through
working registers and indirect addressing modes.
R253 RP
D7 D6 D5 D4 D3 D2 D1 D0
Default Setting After Reset = 00000000
Expanded Register Group
Working Register Group
Figure 19. Register Pointer Register
Location
R255
R254
R253
R252
R251
R250
R249
R248
R247
R246
R245
R244
R243
R242
R241
R240
R239
R4
R3
R2
R1
R0
Stack Pointer (Bits 7-0)
Stack Pointer (Bits 15-8)
Register Pointer
Program Control Flags
Interrupt Mask Register
Interrupt Request Register
Interrupt Priority Register
Ports 0-1 Mode
Port 3 Mode
Port 2 Mode
T0 Prescaler
Timer/Counter0
T1 Prescaler
Timer/Counter1
Timer Mode
Serial I/O
Identifiers
SPL
SPH
RP
FLAGS
IMR
IRQ
IPR
P01M
P3M
P2M
PRE0
T0
PRE1
T1
TMR
SIO
General-Purpose
Registers
Port 3
P3
Port 2
P2
Port 1
P1
Port 0
P0
Figure 18. Register File
20