21. List the operation modes of 8255? a) IO Mode i. Mode 0- Simple Input/Output. ii. Mode 1- Strobe Input/Output (handshake mode) iii. Mode 2- Strobe bidirectional mode b) Bit Set/Reset Mode. 22. What is a control word It is a word stored in a register (control register) used to control the operation of a program digital device. 23. What is the purpose of control word written to control register in 8255? The control words written to control register specify an IO function for each IO port. The bit D of the control word determines either the IO functions of the BSR function.
