The Controller 
Repeater controller uses a PTT and a CAS controlled audio switch. A CW IDer with timer was used for repeater identification. An 8870 chip decoded DTMF tones to change controller parameters. The repeater used PLL tones to control carrier access .
The controller was implemented using a state machine and the size of the program and its features pushed the memory capacity of the microprocessor. The 8870 DTMF decoder was an attempt the keep some of the processing off the microcontroller. The controller worked well and gave remote control features to the repeater.
Some programmer were working on Real-time operating system (RTOS) to handle multitasking. RTOS was a nice feature to have for a project like this. The repeater controller became much easier to implement with Raspberry Pi.
AA5OY 