Core PLC (Programmable Logic Controller) board
For programming the board/microcontroller/pic16f877A pickit 2 programmer is made on the board. Pickit 2 is a programmer by microchip used to program its pic microcontrollers. Pickit 2 uses icsp interface to program the target microcontroller. Icsp interface of pickit 2 programmer is connected with the pic16f877a microcontroller using DIP switches. When ever a new logic is desired to be downloaded in the processor, switch on the dip switches. Dip switches are installed to prevent the controller pins from interference by the pickit 2 programmer circuit. I have a separate tutorial on pickit 2 programmer made at home. Visit the link for more information
Microchip Pickit 2 Programmer made at home – Diy Project
The Resistors on the front side of the pcb that are not aligned are added after the pcb printing. These resistors are added as pull-ups to the input pins. While testing the circuit i found that the input pins of pic16f877 floats so i added the pull-up resistors. On pcb back i added some extra tin/lead on the traces to remove any resistance created in them during the etching process.
Circuit/Block diagram and Pcb of Core PLC board.
PLC status board
Some tutorials that will help you in understanding the interfaces and working of the status board.