z08617 ZiLOG Semiconductor, z08617 Datasheet - Page 11

• Manufacturer Part Number: z08617
• Description: Nmos Z8 8-bit Mcu Keyboard Controller
• Manufacturer: ZiLOG Semiconductor

FUNCTIONAL DESCRIPTION (Continued)
Register File. The register file (Figure 10) consists of four
I/O port registers, 124 general-purpose registers and 16
control and status registers (R3-R0, R127-R4, and R255-
R240, respectively). The instructions can access registers
directly or indirectly through an 8-bit address field. This
allows short, 4-bit register addressing using the Register
LOCATION
R255
R254
R253
R252
R251
R250
R249
R248
R247
R246
R245
R244
R243
R242
R241
R240
R127
Figure 10. Register File Configuration
R4
R3
R2
R1
R0
General-Purpose Register (Bits 7-0)
Interrupt Request Register
Interrupt Priority Register
Interrupt Mask Register
Stack Pointer (Bits 7-0)
Program Control Flags
Not Implemented
General-Purpose
Register Pointer
Timer/Counter0
Timer/Counter1
Ports 1-0 Mode
T0 Prescaler
T1 Prescaler
Port 3 Mode
Port 2 Mode
Timer Mode
Reserved
Registers
Port 3
Port 2
Port 1
Port 0
IDENTIFIERS
SPL
GPR
RP
FLAGS
IMR
IRQ
IPR
P01M
P3M
P2M
PREQ
T0
PRE1
T1
TMR
P3
P2
P1
P0
Pointer (Figure 11). In the 4-bit mode, the register file is
divided into nine working-register groups, each occupy-
ing 16 continuous locations. The Register Pointer ad-
dresses the starting location of the active working-register
group.
Figure 11. Register Pointer Configuration
FF
F0
1F
10
2F
20
0F
00
•
•
•
•
•
•
•
•
•
•
•
The upper nibble of the register file address
provided by the register pointer specifies
the active working-register group.
r7 r6 r5 r4
Register Group F
Specified Working
Register Group 1
Register Group 0
Register Group
I/O Ports
•
•
•
r3 r2 r1 r0
Z08617 NMOS Z8
K
EYBOARD
R253
(Register Pointer)
The lower nibble
of the register
file address
provided by the
instruction points
to the specified
register.
R15 to R0
R15 to R0
R15 to R4
R3 to R0
®
C
ONTROLLER
8-B
IT
MCU
11