EM78468AQ EMC [ELAN Microelectronics Corp], EM78468AQ Datasheet - Page 14

• Manufacturer Part Number: EM78468AQ
• Description: 8-BIT Microcontroller
• Manufacturer: EMC [ELAN Microelectronics Corp]

EM78468
8-BIT Microcontroller
10 •
4.1 Operational Registers
4.1.1
4.1.2
4.1.3
R0 is not a physically implemented register. It is used as indirect addressing pointer. Any
instruction using R0 as register actually accesses the data pointed by the RAM Select
Register (R4).
Increases by an external signal edge applied to TCC, or by the instruction cycle clock.
Written and read by the program as any other register.
* The structure is depicted in Fig. 3
* Generates 4K × 13 on-chip ROM addresses to the relative programming instruction
codes.
* "JMP" instruction allows direct loading of the low 10 program counter bits.
* "CALL" instruction loads the low 10 bits of the PC and PC+1, then push it into the stack.
* "RET'' ("RETL k", "RETI") instruction loads the program counter with the contents at the
top of stack.
* "MOV R2, A" allows the loading of an address from the A register to the PC. The
contents of the ninth and tenth bits do not change.
* "ADD R2, A" allows a relative address be added to the current PC.
* The most significant bit (A10~A11) will be loaded with the content of bits PS0~PS1 in
the Status register (R3) upon execution of a "JMP'' or "CALL'' instruction.
R0/IAR (Indirect Addressing Register)
(Address: 00h)
R1/TCC (Time Clock /Counter)
(Address: 01h)
R2/PC (Program Counter)
(Address: 02h)
(This specification is subject to change without further notice)
Product Specification (V1.1) 04.11.2005