em78p809n ELAN Microelectronics Corp, em78p809n Datasheet - Page 13

• Manufacturer Part Number: em78p809n
• Description: 8-bit Microcontroller
• Manufacturer: ELAN Microelectronics Corp

Product Specification (V1.0) 07.26.2005
(This specification is subject to change without further notice)
GRBS1
GRBS1
Bit 7
Bit 7
R4/RSR − RAM Select Register ( Address: 04h )
Register Bank 0 ( R3 bits (7, 6) = (0, 0) )
SCR − System Control Register, Program ROM Page Select ( Address: 05h )
Bit 6 (PS2) ~ 4 (PS0) : ROM Page select bits. User can use PAGE instruction (e.g.
Bit 3 (P) : Power down bit. Set to “1” during power on or by a "WDTC" command
Bit 2 (Z) : Zero flag. Set to "1" if the result of an arithmetic or logic operation is
Bit 1 (DC) : Auxiliary carry flag
Bit 0 (C) : Carry flag
Bit 7: 6 ( GRBS1 : GRBS0 ) : determine which general purpose banks are
Bit 5: 0 ( RSR5 : RSR0 ) : are used to select the registers (address: 00h~3Fh) in
0
0
0
1
1
RBS0
Bit 6
activated among the 4 banks. Use BANK instruction (e.g. BABK 1) to
change bank.
Bit 6
PS2
the indirect addressing mode. If no indirect addressing is used, the RSR
can be used as an 8-bit general-purpose read/write register. See the
data memory configuration in Fig. 3.
and reset to “0” by a "SLEP" command.
zero.
PAGE 1) or set PS2~PS0 bits to change the ROM page.
executing a "JMP", "CALL", or other instructions which cause the
program counter to change (e.g. MOV R2, A), PS2~PS0 are loaded into
the 13th to 11th bits of the program counter and select one of the
available program memory pages.
instruction does not change the PS2~PS0 bits. That is, return will
always be to the page from where the subroutine was called, regardless
of the PS2~PS0 bits current setting.
GRBS0
0
1
0
1
RSR5
Bit 5
Bit 5
PS1
General Purpose Register Bank (Address 20H ~ 3FH)
RSR4
Bit 4
Bit 4
PS0
RSR3
Bit 3
Bit 3
0
Note that RET (RETL, RETI)
Bank 0
Bank 1
Bank 2
Bank 3
RSR2
Bit 2
Bit 2
1
8-Bit Microcontroller
RSR1
Bit 1
Bit 1
SIS
EM78P809N
RSR0
Bit 0
Bit 0
REM
When
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