(2) it can be made to work with any speed 805x and 8255
That is an outright misconception. I fear that you're saying that sort of thing from a base of ignorance.

The 8255 can NOT be "be made to work" with many (most?) newer derivatives without slowing them down.

You keep suggesting that a novice get a hold of a steam-driven variant of the '51, attach all kind of external memory and peripherals and see this ancient setup do something. That, in my opinion, is not a 101 item. If you want to include it in 103 from a historical perspective, that may be OK, but to start out with a very complex setup, when a simple one is availabe, is not the way to get someone going.

the issue is that 'I/O expansion' is RARELY necessary when you do not live in the past and thus do not have internal memory and, for that reason, if you have a need for I/O expansion, the right answer is "forget it, ues a chip with sufficient internal resources and get all the pins for I/O". If a novice need more than 32 I/O pins, 8K fof RAM and 64k of code memory, he is, most likely, way beyond what a novice should attempt. If a seasoned developer meed more than 32 pins, I doubt he would even consider the 8255.

There is no reason whatsoever for a novice to use external memory, it is not needed for any novice project.

There has been a plethora of posts (DO NOT ask me to find them, you, yourself state the inabilities of the search), "why does the 8255 not work with my '51?" which have been related to speed. This, typically has bee from downloading some code from the net, not realizing that what works at 8MHz/12 may not work at 20MHz/6.

Sure, you can put a mule in front of a Porsche, and, indeed, the Porsche will move, - if you can make the mule move :) - but is that taking advantage of the Porsches abilities?

Now, for the argument "internal memory chips are difficult to obtain where I live" GET WITH IT "difficult" does not mean "impossible" and if you can not handle things being "difficult" sometimes, stay away from microcontrollers.

Erik