EM73962A
4-BIT MICROCONTROLLER
PROGRAM COUNTER (16K ROM) for EM73962A
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
SF=0; PC← PC +1( branch condition not satisified )
PC Original PC value + 1
a
a
a
a
a
a
LBR a
Object code: 1100 aaaa aaaa aaaa
Condition: SF=1; PC ← PC 12.a ( branch condition satisified )
Hold
+2
PC
a
a
a
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
SF=0 ; PC ← PC + 3 ( branch condition not satisified )
PC Original PC value + 3
a
a
a
a
a
a
a
a
a
a
a
a
(2) Subroutine instruction:
SCALL a
Object code: 1110 nnnn
Condition : PC ← a ; a=8n+6 ; n=1..Fh ; a=86h, n=0
PC 0
LCALL a
0
0
0
0
a
a
a
a
a
1
1
0
Object code: 0100 0aaa aaaa aaaa
Condition: PC ← a
* This specification are subject to be changed without notice.
10.8.2001
8
ELAN [ ELAN MICROELECTRONICS CORP ]
