EM78P330 datasheet(13/112 Pages) EMC

13 / 112 page

EM78P330/331N

8-Bit Microprocessor with OTP ROM

Product Specification (V 1.1) 03.13.2007

• 7

(This specification is subject to change without further notice)

"CALL" instruction loads the lower 10 bits of the PC, and then PC+1 is pushed onto

the stack. Thus, the subroutine entry address can be located anywhere within a

page.

"RET" ("RETL k", "RETI") instruction loads the program counter with the contents

of the top of stack.

"ADD R2, A" allows a relative address to be added to the current PC, and the ninth

and above bits of the PC will increase progressively.

"MOV R2, A" allows loading of an address from the "A" register to the lower 8 bits of

the PC, and the ninth and tenth bits (A8 ~ A9) of the PC will remain unchanged.

Any instruction (except “ADD R2,A”) that is written to R2 (e.g., "MOV R2, A", "BC

R2, 6",

⋅⋅⋅⋅⋅) will cause the ninth bit and the tenth bit (A8 ~ A9) of the PC to remain

unchanged.

In the case of EM78P330N, the most three significant bits (A12,A11 and A10) will

be loaded with the content of PS2,PS1 and PS0 in the status register (R3) upon

execution of a "JMP", "CALL", or any other instructions set which write to R2.

All instructions are single instruction cycle (fclk/2 or fclk/4) except for the

instructions that are written to R2. Note that these instructions need one or two

instructions cycle as determined by Code Option Register CYES bit.

EM78P330 Datasheet(PDF) 13 Page - ELAN Microelectronics Corp