Specifications

S1C6S2N7 TECHNICAL SOFTWARE EPSON II-27
CHAPTER 3: PERIPHERAL CIRCUITS (I/O Ports)
• Loading P00–P03 output data into A register
Label Mnemonic/operand Comment
LD Y,0FCH ;Set the address of input/output
;port control register
OR MY,0001B ;Set as output port
LD Y,0F6H ;Set the address of port
LD A,MY ;A register ← P00–P03
As shown in Figure 3.4.2, the four instruction steps above
load the data of the I/O ports into the A register.
P03 P02 P01 P00
Data register
P00
Data register
P01
Data register
P02
Data register
P03
A register
D3 D2 D1 D0
Fig. 3.4.2
Control of I/O port (input)
Data can be loaded from the I/O port into the B register or
MX instead of the A register.