Previously, i use 877 in my project. However, while i plotting the PCB layout, i realise 877 is waste of space. (of course, i am using the DIP). As there are many unused pins in my 877, i replace it with 876 and just made some slight change in my program.
Why microchip produce such wide range variety of microcontroller??
cost is a factor. 877 is more expensive, and making the cost of PCB higher.
so, if you dont need so much pins, why would u wan to use 877.