Z86L7808PSC View Datasheet(PDF) - Zilog
Part Name
Description
MFG CO.
'Z86L7808PSC' PDF : 59 Pages View PDF
Zilog
Z86L78
IR/Low-Voltage Microcontroller
Register File. The register file (group 0) consists of four Registers E0-EF of Bank 0 are only accessed through
I/O port registers, 236 general-purpose registers, and 16 working registers and indirect addressing modes.
1 control and status registers (R0-R3, R4-R239, and R240-
R255, respectively), Plus two expanded registers groups Stack. The Z86L78 internal register file is used for the
(Banks D and F). Instructions can access registers directly stack. An 8-bit Stack Pointer (R255) is used for the internal
or indirectly through an 8-bit address field. This allows a stack that resides within the general-purpose registers
short, 4-bit register address using the Register Pointer (R4-R239). SPH is used as a general-purpose register
(Figure 15). In the 4-bit mode, the register file is divided only when using internal stacks. Note: Only the lower 256
into 16 working register groups, each occupying 16 contin- bytes of RAM may be used for stack operations.
uous locations. The Register Pointer addresses the start-
ing location of the active working register group. Note:
Note: When SPH is used as a general-purpose register
and Port 0 is in address mode, the contents of SPH will be
loaded into Port 0 whenever the internal stack is accessed.
r7 r6 r5 r4
r3 r2 r1 r0 R253
The upper nibble of the register file address
provided by the register pointer specifies
the active working-register group
FF
R15 to R0
F0
DS97LVO0701
Specified Working
Register Group
2F
20
1F
Register Group 1
10
0F
Register Group 0
00
I/O Ports
The lower nibble
of the register
file address
provided by the
instruction points
to the specified
register
R15 to R0
R15 to R4
R3 to R0
Figure 17. Register Pointer
2-23
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