CHAPTER 3 REGISTERS

3.3.2Byte Data Transfer and Operation of Accumulator (A) and Temporary Accumulator (T)

When data transfer to the accumulator (A) is performed byte-by-byte, the transfer data is stored in the AL. Automatic data transfer to the temporary accumulator (T) is also performed byte-by-byte and only the contents of the original AL are stored in the TL. Neither the upper 8 bits of the accumulator nor the temporary accumulator are affected by the transfer. Only the lower 8 bits are used for byte operation between the accumulator and temporary accumulator. None of the upper 8 bits of the accumulator or temporary accumulator are affected by the operation.

Example of Operation of Accumulator (A) and Temporary Accumulator (T) in Byte Data Processing

An example of addition with carry of 8-bit data stored at addresses 1280H and 0042H is shown below.

MOV A,

0042H

-

MOV A,

1280H

-

ADDC A

-

Figure 3.3-8shows the operation of the accumulator and temporary accumulator when the above example is executed.

Figure 3.3-8 Operation of Accumulator and Temporary Accumulator in Byte Data Processing

Before execution

Last result

AABXXH

TCDXXH

 

RAM

1280H

 

56H

...

 

 

...

0042H

 

EFH

 

 

 

 

A

ABEFH

T

CDXXH

 

 

RAM

1280H

56H

 

...

...

0042H

EFH

A

AB56H

T

CDEFH *1

 

 

RAM

1280H

56H

 

...

...

0042H

EFH

+

 

 

A

AB*246H

 

 

 

 

 

 

 

 

 

 

 

 

 

CF

1

 

 

T

CDEFH

 

 

 

 

 

 

 

 

RAM

 

 

 

 

1280H

56H

 

 

 

 

 

 

 

...

 

 

...

 

 

 

 

 

0042H

EFH

 

 

 

 

 

 

 

 

 

 

*1 The TH does not change when there is automatic data transfer to the temporary accumulator. *2 The AH is not changed by the result of the addition of the AL, TL, and CF.

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Fujitsu F2MC-8FX manual Abxxh Cdxxh RAM