Tandy 1000 Basic Reference Manual page 180

Chapter 10 I
BASIC Ke.ywords
INP
Function
INP(port)
Returns the byte read from port.
Port may be any integer from 0 to 65535.
INP
is the complementary function of the OUT statement.
Example
1 0 0 A=INP(255)
returns the byte read from port 255 into variable A.
178