Panasonic F77G, MN101C77C user manual Registers for Data, DW0, DW1

Models: F77G MN101C77C

1 544
Download 544 pages 59.61 Kb
Page 59
Image 59

Chapter 2 CPU Basics

„Address Registers (A0, A1)

These registers are used as address pointers specifying data locations in memory. They support the operations involved in address calculations (i.e. addition, subtraction and comparison). Those pointers are 2 bytes data. Transfers between these registers and memory are always in 16-bit units. Either odd or even address can be transferred. At reset, the value of address register is undefined.

150

Address Registers

A0

A1

„Stack Pointer (SP)

This register gives the address of the byte at the top of the stack. It is decremented during push opera- tions and incremented during pop operations. Ar reset, the value of SP is undefined.

Stack Pointer

150

SP

2-1-6 Registers for Data

Registers for data include four data registers (D0, D1, D2, D3).

„Data Registers (D0, D1, D2, D3)

Data registers D0 to D3 are 8-bit general-purpose registers that support all arithmetic, logical and shift operations. All registers can be used for data transfers with memory.

The four data registers may be paired to form the 16-bit data registers DW0 (D0+D1) and DW1 (D2+D3). At reset, the value of Dn is undefined.

15

8

7

 

0

Data

D1

 

D0

DW0

 

 

 

 

registers

D3

 

D2

DW1

 

 

Overview II - 7

Page 59
Image 59
Panasonic F77G, MN101C77C user manual Registers for Data, DW0, DW1