Z86L71 datasheet(22/61 Pages) ZILOG

22 / 61 page

Z86L70/71/75/C71

IR/Low-Voltage Microcontroller

Zilog

1-22

P R E L I M I N A R Y

DS97LVO0500

RAM/Register File. The register file (group 0) consists of

four I/O port registers, 236 general purpose registers, and

16 control and status registers (R0-R3, R4-R239, and

R240-R255, respectively), plus two expanded registers

group (Banks D and F). 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: Registers E0-EF of Bank 0 are only accessed

through working registers and indirect addressing modes.

Stack. The Z86L7X internal register file is used for the

stack. An 8-bit Stack Pointer (R255) is used for the internal

stack that resides in the general-purpose registers (R4-

R239).

Figure 15. Register Pointer

D7 D6 D5 D4 D3 D2 D1 D0

Expanded Register Bank

File Pointer

Working Register

Pointer

R253 RP

Default Setting After

Reset = 0000 0000

Figure 16. Register Pointer

The upper nibble of the register file address

provided by the register pointer specifies

the active working-register group

R253

I/O Ports

Specified Working

The lower nibble

of the register

file address

provided by the

instruction points

to the specified

R15 to R0

R15 to R4 *

R3 to R0 *

* RP = 00: Selects Register Group 0, Working Register 0.

Z86L71 Datasheet(PDF) 22 Page - Zilog, Inc.

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