Interface Module

• The 2 msb address bits are fed to one 4028 (through a board select jumper) to enable the 2nd 4028
• Up to 4 interface modules may be daisy chained together, each with a different board select jumper position
• The next 2 bits of address are fed to the 2nd 4028 to select which 4016 will be enabled
• Thus 4 analog lines from a selected 4016 will drive the 4 analog lines back to the controller A/D
• Selection of which of the 4 A/D lines is determined by the lsb 2 bits of the address within the controller software

• Interface Module use a pair of 4028 decoders