dp8344b National Semiconductor Corporation, dp8344b Datasheet - Page 144

• Manufacturer Part Number: dp8344b
• Description: Biphase Communications Processor?bcp
• Manufacturer: National Semiconductor Corporation

Figure 6-3
6 0 Reference Section
LCALL Conditional Long Call
Syntax
LCALL Rs p s nn
Affected Flags
None
Description
If the bit in position p of register Rs is equal to the bit s then
push the Program Counter the ALU flags the Global Inter-
rupt Enable bit GIE and the current register bank selec-
tions onto the internal Address Stack Following the push
transfer control to the instruction at the absolute memory
address nn The operand Rs may specify any active CPU
register The value of p may be from 0 to 7 where 0 corre-
sponds to the LSB of Rs and 7 corresponds to the MSB of
Rs The absolute value nn is 16 bits long (range 0 to 64k)
therefore all of instruction memory can be addressed
Example
Call the ‘‘Load Xmit’’ subroutine when the Transmitter FIFO
Empty flag TFE of the Network Command Flag register
Instruction Format
T-states
(2
Bus Timing
Operation
If Rs p
End if
NCF is ‘‘1’’
1
15
15
EXX
LCALL NCF 7 1 Load Xmit
PC
nn
a
x
0
x
2)
0
e
GIE
Opcode
PC
Address Stack
0 0
s then
0
1
ALU flags
1
1
s
8
nn
register bank selections
register absolute
7
p
select main A alt B
If TFE
(Continued)
4
e
1 call
Rs
0
0
144
Figure 6-3
LCALL Unconditional Long Call
Syntax
LCALL nn
Affected Flags
None
Description
Pushes the Program Counter the ALU flags the Global In-
terrupt Enable bit GIE and the current register bank selec-
tions onto the internal Address Stack then unconditionally
transfers control to the instruction at the absolute memory
address nn The value of nn is 16 bits long (range 0 to
64k) therefore all of instruction memory can be addressed
Example
Transfer control to the subroutine ‘‘Send it all’’ which could
be located anywhere in instruction memory
Instruction Format
T-states
(2
Bus Timing
Operation
PC
nn
1
15
15
LCALL
x
x
a
1
2)
GIE
PC
Address Stack
0
0
Send it all
ALU flags
1
1
absolute
1
Opcode
0
register bank selections
nn
1
0
0
0
0
0
0
0
0
0