71M6403-IGTR TERIDIAN [Teridian Semiconductor Corporation], 71M6403-IGTR Datasheet - Page 18

• Manufacturer Part Number: 71M6403-IGTR
• Description: Electronic Trip Unit
• Manufacturer: TERIDIAN [Teridian Semiconductor Corporation]

Accumulator (ACC, A): ACC is the accumulator register. Most instructions use the accumulator to hold the operand. The
mnemonics for accumulator-specific instructions refer to the accumulator as “A”, not ACC.
B Register: The B register is used during multiply and divide instructions. It can also be used as a scratch-pad register to hold
temporary data.
Program Status Word (PSW):
Stack Pointer (SP): The stack pointer is a 1-byte register initialized to 0x07 after reset. This register is incremented before
PUSH and CALL instructions, causing the stack to begin at location 0x08.
Data Pointer: The data pointer (DPTR) is 2 bytes wide. The lower part is DPL, and the highest is DPH. It can be loaded as a 2-
byte register (MOV DPTR,#data16) or as two registers (e.g. MOV DPL,#data8). It is generally used to access external code or
data space (e.g. MOVC A,@A+DPTR or MOVX A,@DPTR respectively).
Program Counter: The program counter (PC) is 2 bytes wide initialized to 0x0000 after reset. This register is incremented
during the fetching operation code or when operating on data from program memory.
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PSW.7
PSW.6
PSW.5
PSW.4
PSW.3
PSW.2
PSW.1
PSW.0
Bit
MSB
CV
Symbol
RS1
RS0
AC
CV
AC
OV
F0
P
-
Function
Carry flag
Auxiliary Carry flag for BCD operations
General purpose Flag 0 available for user. Not to be confused with the F0 flag
in the CE STATUS register.
Register bank select control bits. The contents of RS1 and RS0 select the working
register bank:
Overflow flag
User defined flag
Parity flag, affected by hardware to indicate odd / even number of “one” bits in the
Accumulator, i.e. even parity.
F0
RS1/RS0
©
Table 7: PSW Register Flags
RS1
2006 TERIDIAN Semiconductor Corporation
Table 8: PSW bit functions
00
01
10
11
RS
Bank selected
Bank 0
Bank 1
Bank 2
Bank 3
OV
Electronic Trip Unit
-
(0x00 – 0x07)
(0x08 – 0x0F)
(0x10 – 0x17)
(0x18 – 0x1F)
P
Location
LSB
71M6403
SEPTEMBER 2006
REV 1.0