New 65C816 datasheets say that Vih (for the data bus in particular) is 0.8Vdd, i.e. not TTL-compaible.
Old data sheets (for example, the one published in Apple IIgs Hardware Reference) say that at 5V +/- 5%, Vih is 2.0V.
Are old 65C816s TTL compatible? Was there some kind of change?
There has been a lot of talk about this but I can't find anything conclusive.