80C39 is a Cmos Version of 8048 the one that preceded 8031-8051. MCS48 is the set for that, MCS51 is the current set. The circuit of the Analog Front End was a V-F Converter.
Here is an example project for 80C39-8748-8749 microcontroller. This code was written by me, and it works. But the documentation is not complete or may have errors.
80C39-8749 MCS-48 Examples and code.
Process Controller code here 80C39 Code for MCS48. The circuit for these are on this page along with other circuits.
This may be difficult to put together now. But the code and hardware is near compatible to 8051 uC. Now there are may types of ADC and uC.