EM78P458/459
OTP ROM
4. R3 (Status Register)
7 | 6 | 5 | 4 |
| 3 | 2 | 1 | 0 |
CMPOUT | PS1 | PS0 | T |
| P | Z | DC | C |
• Bit 7 (CMPOUT) the result of the comparator output. |
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• Bit 6 (PS1) ~ 5 (PS0) Page select bits. PS0~PS1 are used to select a program memory page. When executing a "JMP", "CALL", or other instructions which cause the program counter to be changed (e.g. MOV R2, A), PS0~PS1 are loaded into the 11th and 12th bits 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~PS1 bits. That is, the return will always be to the page from the place where the
subroutine was called, regardless of the current setting of PS0~PS1 bits.
PS1 | PS0 | Program memory page [Address] |
0 | 0 | Page 0 |
0 | 1 | Page 1 |
1 | 0 | Page 2 |
1 | 1 | Page 3 |
• Bit 4 (T)
• Bit 3 (P)
• 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
5. R4 (RAM Select Register)
• Bits 0~5 are used to select registers (address: 00~3F) in the indirect address mode.
• Bit 6 is used to select bank 0 or bank 1.
• Bit 7 is a
• See the configuration of the data memory in Fig. 4.
6. R5 ~ R6 (Port 5 ~ Port 6)
• R5 and R6 are I/O registers.
7. R7 ~ R8
• All of these are
This specification is subject to change without prior notice. | 10 | 07.01.2003 (V1.3) |