EM73982 View Datasheet(PDF) - ELAN Microelectronics
Part Name
Description
MFG CO.
'EM73982' PDF : 41 Pages View PDF
EM73982
4-BIT MICROCONTROLLER
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 a a a a a a
SF=0; PC← PC +1 (branch condition not satisified)
PC
Original PC value + 1
LBR a
Object code: 1100 aaaa aaaa aaaa
Condition: SF=1; PC ← PC 12.a (branch condition satisified)
PC
a Hold
+2
aa
a
a
aa
a
a
a
a
a
SF=0; PC← PC +2 (branch condition not satisified)
PC
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 a a a a a a a a a a a a a
SF=0 ; PC ← PC + 3 (branch condition not satisified)
PC
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 0 0 0 0 0 a a a a a 1 1 0
LCALL a
Object code: 0100 0aaa aaaa aaaa
Condition: PC ← a
* This specification are subject to be changed without notice.
11.30.2001 13
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