EM73866
4-BIT MICRO-CONTROLLER FOR LCD PRODUCT
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 instruction.
For BRANCH and CALL instructions, PC is changed by instruction indicated. PC can only indicate the address
from 0000h-1FFFh.
(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
a
a
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
(2) Subrountine instruction:
a
a
a
a
a
a
a
a
a
a
a
a
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
a
a
a
* This specification are subject to be changed without notice.
12.29.1999
8
ELAN [ ELAN MICROELECTRONICS CORP ]
