USER'S GUIDE

PROGRAM STATUS WORD REGISTER

 

 

 

 

 

 

Label:PSW

 

 

 

 

 

Register Address: 0D0H

 

D7

D6

D5

D4

D3

D2

D1

D0

 

 

 

 

 

 

 

 

 

 

C

AC

F0

 

RS1

RS0

OV

 

 

P

 

 

 

 

 

 

 

 

 

 

All of the bits in PSW except parity are read/write and are cleared to 0 on any type of reset. The Parity bit is read only and is cleared to 0 on any type of reset.

Bit Description:

PSW.7:

C

 

 

ªCarryº:

Set when the previous operation resulted in a carry (during addition) or a

 

borrow (during subtraction). Otherwise cleared.

PSW.6:

AC

 

 

ªAuxiliary-Carryº:

Set when the previous operation resulted in a carry (during addition) or a

 

borrow (during subtraction) from the low±order nibble. Otherwise cleared.

PSW.5:

F0

 

 

ªUser Flag 0º:

General±purpose flag bit which can be set or cleared as needed.

PSW.4±3:

R1±R0

 

 

ªRegister Bank Selectº:

Used to select an 8±byte bank of registers within the Data Register space to

 

be assigned as R0±R8 in subsequent instructions. The 8±byte bank starting

 

address selection is as follows:

 

R1

R0

Data Register Address (R0)

 

0

0

00H

 

0

1

08H

 

1

0

10H

 

1

1

18H

PSW.2:

OV

 

 

ªOverflowº:

Set when a carry was generated into the high±order bit but not a carry out of

 

the high±order bit as a result of the previous operation, and visa±versa. OV

 

is normally used in 2's complement arithmetic.

PSW.0:

P

 

 

ªParityº:

Set if the modulo±2 sum of the eight bits of the accumulator is 1 (odd parity);

 

cleared on even parity.

 

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Mitsubishi DS907x SIP, DS5000TK manual Program Status Word Register, LabelPSW Register Address 0D0H