IBM EM78P259N/260N manual 5 R4 RAM Select Register, Bit 4 T, Bits 5~0

Models: EM78P259N/260N

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EM78P259N/260N

8-Bit Microprocessor with OTP ROM

6.1.4

R3 (Status Register)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bit 7

 

Bit 6

Bit 5

 

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

RST

 

IOCS

PS0

 

T

P

Z

DC

C

Bit 7 (RST): Bit of reset type

Set to “1” if wake-up from sleep on pin change, comparator status change, or AD conversion completed. Set to “0” if wake-up from other reset types

Bit 6 (IOCS): Select the Segment of IO control register 0 = Segment 0 (IOC50 ~ IOCF0) selected 1 = Segment 1 (IOC51 ~ IOCC1) selected

Bit 5 (PS0): Page select bits. PS0 is used to select a program memory page. When executing a "JMP," "CALL," or other instructions which cause the program counter to change (e.g., MOV R2, A), PS0 is loaded into the 11th bit of the program counter where it selects one of the available program memory pages. Note that RET (RETL, RETI) instruction does not change the PS0 bit. That is, the return address will always be back to the page from where the subroutine was called, regardless of the current PS0 bit setting.

PS0

Program Memory Page [Address]

0

1

Page 0 [000-3FF]

Page 1 [400-7FF]

Bit 4 (T):

Time-out bit. Set to “1” by the "SLEP" and "WDTC" commands or during

 

 

power on; and reset to “0” by WDT time-out (see Section 6.5.2, The T

 

 

and P Status under STATUS Register for more details).

Bit 3

(P):

Power-down bit. Set to “1” during power-on or by a "WDTC" command

 

 

and reset to “0” by a "SLEP" command (see Section 6.5.2, The T and P

 

 

Status under STATUS Register for more details).

Bit 2

(Z):

Zero flag. Set to "1" if the result of an arithmetic or logic operation is

 

 

zero.

Bit 1

(DC):

Auxiliary carry flag

Bit 0

(C):

Carry flag

6.1.5 R4 (RAM Select Register)

Bit 7:

Set to “0” all the time

Bit 6:

Used to select Bank 0 or Bank 1 of the register

Bits 5~0:

Used to select a register (Address: 00~0F, 10~3F) in indirect addressing

 

mode

See the table under Section 6.1.3.1, Data Memory Configuration for data memory

configuration.

 

 

 

8 •

Product Specification (V1.2) 05.18.2007

 

(This specification is subject to change without further notice)

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IBM EM78P259N/260N manual 5 R4 RAM Select Register, Bit 4 T, Bits 5~0