EM73P982 datasheet(13/41 Pages) EMC

13 / 41 page

* This specification are subject to be changed without notice.

EM73P982

4-BIT MICROCONTROLLER

12.25.2001

PROGRAM COUNTER

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

12-6.a (branch condition satisified)

PC Hold original PC value+1

aaaaaa

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

← PC

12.a (branch condition satisified)

PC Hold a

a aaaaaa

SF=0; PC

← PC +2 (branch condition not satisified)

Original PC value + 2

SLBR a

Object code: 0101 0101 1100 aaaa aaaa aaaa (a:1000h~1FFFh)

0101 0111 1100 aaaa aaaa aaaa (a:0000h~0FFFh)

Condition: SF=1; PC

← a (branch condition satisified)

PC aaaaaaaaaaaa

SF=0 ; PC

← PC + 3 (branch condition not satisified)

Original PC value + 3

(2) Subroutine instruction:

SCALL a

Object code: 1110 nnnn

Condition : PC

← a ; a=8n+6 ; n=1..Fh ; a=86h, n=0

PC 00000

aaaaa1

LCALL a

Object code: 0100 0aaa aaaa aaaa

Condition: PC

← a

EM73P982 Datasheet(PDF) 13 Page - ELAN Microelectronics Corp

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