Specifications

S1C6S2N7 TECHNICAL SOFTWARE EPSON II-15

CHAPTER 3: PERIPHERAL CIRCUITS (Input Ports)

The S1C6S2N7 has one 4-bit input port (K00–K03). Input

port data can be read as a 4-bit unit (K00–K03).

The state of the input ports can be obtained by reading the

data (bits D3, D2, D1, D0) of address 0E0H. The input ports

can be used to send an interrupt request to the CPU via the

input interrupt condition flag. See Section 3.10 "Interrupt

and Halt", for details.

• Loading K00–K03 into the A register

Label Mnemonic/operand Comment

LD Y,0E0H ;Set address of port

LD A,MY ;A register ← K00–K03

As shown in Figure 3.1.1, the two instruction steps above

load the data of the input port into the A register.

Control of

the input port

Examples of input

port control

program

K03

K02

K01

K00

A register

The data of the input port can be loaded into the B register

or MX instead of the A register.

Fig. 3.1.1

Loading the A register