$ \overline{S_2} - M / \overline{IO}$

• In minimum mode, it carries the $M/ \overline{IO}$ signal to distinguish between memory and IO access.
• In maximum mode, it carries the $\overline{S_2}$ signal. $\overline{S_2}$ is a status signal given to 8288.

$ \overline{S_1} - DT/ \bar{R}$

• In minimum mode, it carries the $DT/ \bar{R}$ signal indicating data transmit or receive.
• This signal goes low for a read operation and high for a write operation.
• In maximum mode it carries the $\overline{S_1}$ signal. $\overline{S_1}$ is status signal given to 8288.
• In maximum mode, bus controller issues the $DT/ \bar{R}$ signal to 8286.

$\overline{S_0} - \overline{DEN}$

• In minimum mode it carries the $\overline{DEN}$ signal and is used to enable the data transceivers.
• In maximum mode it carries the $\overline{S_0}$ signal. $\overline{S_0}$ is a status signal given to 8288.
• In maximum mode, bus controller (IC 8288) generates the DEN signal for 8286. In maximum mode $\overline{S_2} , \overline{S_1}$and $\overline{S_0}$ are used to generate the appropriate control signal.