The $8255$ Programmable Peripheral Interface is used as described below.

$($i$)$ An A$/$D converter is interface to a microprocessor through an $8255.$

The conversion is initiated by a signal from the $8255$ on Port C$.$ A signal on Port

C causes data to be strobe into Port A$.$

$($ii$)$ Two computers exchange data using a pair of $8255$s$.$ Port A works as a

bidirectional data port supported by appropriate handshaking signals.

The appropriate modes of operation of the $8255$ for $($i$)$ and $($ii$)$ would be

$($A$)$ Mode $0$ for $($i$)$ and Mode $1$ for $($ii$)$

$($B$)$ Mode $1$ for $($i$)$ and Mode $2$ for $($ii$)$

$($C$)$ Mode for $($i$)$ and Mode $0$ for $($ii$)$

$($D$)$ Mode $2$ for $($i$)$ and Mode $1$ for $($ii$)$