If you'd address the question before you instead of going on about what you think you know, perhaps this wouldn't be necessary.

OK ... I'm insulting ... I've heard that before ... even from you. OK ... I've been called a bastard before, too. It hasn't hurt me yet.

However, you've got to stop pontificating about what you clearly don't understand.

Any fool can understand that if you run 4KB or more of code (the first 805x's had 4KB, right?) you're doing something, some of the time besides sitting on the external I/O bus. Since you've frequently asserted that the slightly more than 8KB of XRAM on board in your favorite 'F12x's is plenty for you, you won't have external memory, so the bus is available for I/O. I cited the datasheet page that has the parameters for setting the timing on that bus for you yesterday.

Based on that, I asked you to tell us all how much it would slow you down to have an occasional cycle stretched to 230 ns. You apparently couldn't answer. I've shown that, for an infrequent task, such as those valve controls, the effect is very much less significant than the variation in or difference between the best commercial quality crystals. I also showed that for a frequent (60 Hz) 3x update of those 192 controls, it still impacts the system speed by about 0.8%.

Now I ask you, how can you condemn such an arrangement as being "SLOOOOW"? While I'm sure there are tasks for which the 8255 is inappropriate, there are many more for which it's suitable. Is it the "best" way? Well, maybe not, but if it can turn on or off a bit or a byte, or read one, that's all most applications require.

Telling people, just on general principle, or, as you suggest, based on the date code, not to use one, when you don't know why they intend to do that, is just stupid. Now, if you don't object to being considered stupid, then go ahead. You're just telling savvy MCU system designers that your advice is to be taken with a grain of salt.

I think you've made your opinions clear enough to everyone. I doubt anyone will take them as seriously henceforth as they otherwise might.

RE