EM73880 datasheet(6/40 Pages) EMC

6 / 40 page

* This specification are subject to be changed without notice.

EM73880

4-BIT MICRO-CONTROLLER FOR LCD PRODUCT

11.30.2001

Preliminary

PROGRAM COUNTER (8K ROM)

Program counter ( PC ) is composed by a 13-bit counter, which indicates the next executed address for the

instruction of program ROM.

For a 8K - byte size ROM, PC can indicate address form 0000h - 1FFFh, for BRANCH and CALL instrcutions,

PC is changed by instruction indicating.

(1) Branch instruction:

SBR a

Object code: 00aa aaaa

Condition: SF=1; PC

← PC

11-6.a ( branch condition satisified )

Hold original PC value+1

aaaa

SF=0; PC

← PC +1( branch condition not satisified)

Original PC value + 1

LBR a

Object code: 1100 aaaa aaaa aaaa

Condition: SF=1; PC

← a ( branch condition satisified)

aaaaaaaaaaa

SF=0 ; PC

← PC + 2 ( branch condition not satisified )

Original PC value + 2

For example: LDA x ; Acc

← RAM[x]

STA x ; RAM[x]

← Acc

(3) Zero-page addressing mode

For zero-page region, user can using direct addressing to write or do any arithematic, comparsion or bit

manupulated operation directly.

For example: STD #k,y ; RAM[y]

← #k

ADD #k,y; RAM[y]

← RAM[y] + #k

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