25
IN STRUC TION S
Zero Page Bit Relative
Specifies the address of a memory location where the
next Op-Code is located.
The bit position is designated by the high-order three
bits of the Op-Code. The address in the Zero Page
memory location is determined by using Operand I as
low-order byte of the address and 00
16
as the high-
order byte. If the branch condition is satisfied, Oper-
and Il and the Program Counter are added. The result
of this addition is the address in the memory location.
When the branch condition is not satisfied, the next
instruction is executed.
BBC, BBS
Mnemonic
Machine language
∆
BBC
∆
5,$04,
∗
–12
B7
16
04
16
F1
16
Addressing mode
Ze r o Pa g e Bit Re la t iv e
Ad d r e s s in g m o d e :
F u n c tio n :
In s tr u c tio n s :
Ex a m p le :
Decimal
Zero page
designation
0
1
1 1
1 1
0
bit 5
Memory
1
Operand I (04
16
)
*
Address to be
executed next
*–12
0
1
1 1
1 1
0
1
Operand I (04
16
)
*
*+3
Address to be
executed next
0
1
bit 5
Memory
Operand II (F1
16
)
Operand II (F1
16
)
*+3
Jump
04
16
00
16
FF
16
Zero page
04
16
00
16
FF
16
Zero page
Zero page
designation
When the bit 5 at address 04
16
is cleared, jumps to address
*
–12.
When the bit 5 at address 04
16
is set, goes to address
*
+3.
Op-code(B7
16
)
Bit designation
Op-code(B7
16
)
Bit designation
