"Has anyone else used the 80c552??!"

I have.

The 80C552 is very much like a 80c52, but with tons of extra I/O on board. All these I/O circuits come with control registers, located in the SFR area. For instance: it has a hardware I2C interface (nice...) which gives rise to a register called s1buf.

Now here is what your concern is probably about. Because the new I2C serial interface buffer was named s1buf, they RENAMED the original sbuf to s0buf. Same register, different name. And they did that with quite a few registers.

You need to read the datasheet to be sure. It's all there. Apart from the new I/O, any program written for 80c52 can be made to work on an 80c552.

A word of warning: do not fall too much in love with the 80c522, it is an obsolete chip, I don't think it's being produced anymore.

Philip's documentation is excellent as ever, but you need to read THIS document to really get to know the 80C552: http://www.robot-electronics.co.uk/datasheet...VIEW_2.pdf Strangely enough, I couldn't find it on the Philips site, but I knew it existed.