Hi Steve,

I have a huge assembler code library, so reusable code is usually around 60-70%.
Since i started to develope 8051 applications i obeyed strict guidelines about register usage / interface, so even when i design something new with various old modules they'll fit almost seamlessly together.

This is one of the reasons why i never had the urge to switch to C for programming on 8051.

a couple of weeks ago i ported an lcd assembler demo (fancy scroll effects with an HD44780 like I2C LCD) from 8051 to C161 on a rainy sunday afternoon - so i can say what helped me over the years is a modular design with very well documented interfaces.

Cheers, Roger