I grew up in NL having access to an Atari ST, and the (German) Atari ST Profibuch which in my memory covered all there was to these machines and taught me a bit of German too. It was a great combination to learn about computers and worked very well because this book would apply in full to all computers of that series. These machines were simple enough that as a twelve year old, I was able to add a physical pause switch to the computer that would halt the CPU, so I could join dinner without losing progress in the game I was playing. This required soldering on the motherboard! This kind of easy hackery is no longer possible with modern computers, and there is so much complexity that it is easy to get lost in details and not see the whole picture or give up because of that complexity.

For enthusing / teaching a kid we now have things like Arduino and ESP, with the benefit that they are ridiculously cheap. I think these are the modern equivalent of single person computers, except they are not computers :)

Now to find the ESP8266 Profibuch equivalent!

Sure, but the accreted complexity of computing nowadays makes it hard for beginners. I learned on an Apple ][+, a very simple machine. Nowadays even a RaspberryPi is a very complex machine with orders of magnitude more stuff to learn, including path-dependent design choices that are much less comprehensible to someone who wasn't there when they happened.

The last computer I could fully understand, from the processor up to the ROM and the operating system, was an Apple II running DOS 3.3. It's been downhill from there.

I can appreciate the issues with a Smalltalk (or Lisp) environment where everything is exposed to modification at all times. In Smalltalk you used to be able to make true := false and lock the image immediately (nothing would happen because the machine entered a philosophical crisis when it realized nothing was true).

But what if the environment is inpectable, but not immediately changeable? Even though we don't fully understand the video compositing pipeline and how it uses the hundreds of GPU cores, or how the CPU addresses the memory those GPU cores think is the whole universe, we can still explore the parts we care about.

Anyway, not having a workable web browser and an SSH client on Smalltalk rules it out as my daily driver.

ISTM you're painting with too broad a brush. Early PC systems were too resource-constrained for abstraction/modularity/etc. to be practical, and so they were programmed in error-prone, low-level languages. Because the hardware also didn't do much by way of protection, isolation, or preemptive multitasking, many sorts of errors could have arbitrarly large impact.

A couple years ago I bought a Lisp Machine (out of intellectual curiousity). It's not at all accurate to say there's no separation, isolation, abstraction, or modularity in that system. For instance, programs don't draw on the screen by directly twiddling video hardware or write a file by directly poking a hard drive. Instead, programs call well-defined, high-level user interface or file system APIs, respectively. It's true that programs can interfere with one other or corrupt the system, but that doesn't tend to happen due to a coding accident or user error: no more so than than a forkbomb does, I'd say. Unless you're deliberately trying to screw things up, when you make a mistake, you will land in a debugger (where you might be able to fix things and resume), but other programs will keep running. The LispM is neither secure nor resilient in any modern sense, but it's astonishingly robust for a system that omitted conventional timesharing features.

(I don't think the old-school LispMs make sense as end-user systems in the modern world, though, I think one could argue they'd make sense as development environments for Unikernel-style VMs, which, modulo the "V", is basically what the LispM vendors hoped people would use them for.)

The arguments above seem to me to to have two limitations:

• The assumption seems to be that cellphones and tablets are not computers.
• I suspect there is a confusion between "single environment" and "single user" as in the Lisp Machines were "single environment". Reverse example: Amiga/MacOS were "single user".

People don't want single user or simple computers because they are limited by isolation or other nice modern features. They want these because currently Windows, MacOS and some Linux distributions (looking at you Ubuntu) try to make the computer their platform and not yours.