The I/O Section is a scrollable window which is used to do input from the keyboard and printed output. When a program asks for input via the LOAD 11110 (10011110) the simulator pretends that this LOAD from memory location 3010 is actually memory mapped to an input device. What the user sees in the I/O box is a ?. The user then types in the value after the ? - usually a decimal value between -128 and 127 - and, then, that value is put into the accumulator like any other LOAD instruction.
When the program does a STOR 11111 (10111111) the simulator pretends that this STOR to memory location 3110 is actually memory mapped to a display device and the value in the accumulator is output to the I/O screen in decimal. (No ? occurs when output is done.)
Each input or output appears on a separate line in the I/O box.