The megaprocessor is just absolutely wonderful in how it bridges from 'here is a transistor, it lights an LED' to 'here is a computer, it plays tetris'. I always struggled to unwind the layers of abstraction in a modern computer from atoms in the CPU to running python, but being able to just look at a bunch of literal transistors (with LEDs on each gate!) wired up playing tetris shows how a computer really works in such a profound and awe inspiring fashion.
Magic-1 is sort of the next level higher complexity, where it is made out of very simple TTL (most complicated chip function is the ALU--a circuit I had to build as an EE undergrad out of or- and and- gates) and it hosts a webpage. It currently seems to be down, but you can see it on the wayback machine https://web.archive.org/web/20210815180101/http://www.magic-...
I will never forget when I came across that site and realized that I was interacting with a wirewrapped pile of ram and nor gates over the internet. There was even a time when you could telnet in and play some retro text-based adventure games, To this day, the only time I have played Adventure was on Magic-1.
I don't know if the ideas still apply to modern computers, but it's pretty cool understanding how things like addresses are decoded and instructions are constructed and executed at the gate level in a very basic microprocessor.
http://www.oldcomputers.arcula.co.uk/files/images/pdp8104.jp...
It's fairly easy to design a computer like this.
Later TTL/CMOS designs replaced the packaged modules with much smaller 74xx/40xx ICs.
You can make basic logic gates with just diodes and resistors, but you need transistors for inversion, buffering, and a usable flip flop.
That's probably the minimum level for useful computing/calculating. If civilisation has ended and you have no transistors you probably don't have the resources to make glass valves either, so that's going to be a problem.
Of course there's always clockwork...
(I googled this to make sure I wasn't misremembering what I read 40 years ago in an already outdated book at the library and I was suddenly filled with a sense memory of the smell of the interiors of old electric appliances loaded with tubes and dust.)
But yeah, it is a fun "what if".
"What if a super genius with the entirety of wikipedia in his brain were sent back to the stone age? Could he rebuild modern society?"
Yes. Silicon wafers are cut from a monocrystalline boule, a single flawless silicon crystal with no defects or inclusions. A big chunk of silicon atoms, nothing else at all. (Doping happens later) To the extent any physical object can be called "perfect", a semiconductor wafer is perfect.
(Of course after manufacturing it will start picking up embedded hydrogen and helium atoms from cosmic rays and alpha particle background radiation.)
edit: didn’t pay attention that you were talking about the manga. That makes more sense. Sounds highly readable!
Sometimes insects or moths would get stuck in the relays which would screw up the system. This is the origin of the word "bug."
Prior to incorporating logic into electronics, computing machines were hand cranked or motor cranked gear machines. See: https://www.youtube.com/watch?v=fhUfRIeRSZE. The YouTube video literally is a hand cranked portable calculator.
The world you envision has already existed.
It can even do square roots?! That's amazing. And it fits the palm of your hand!
Now we're down to specks of sand calculating so fast they melt without cooling. Seriously wtf.
You need a source of problems to solve, and until you've bootstrapped the rest of society at least to the point where something like high-resolution trigonometric tables, desktop publishing, high-speed accounting, (for example) are needed, the effort isn't going to keep you fed...
As far as mechanical devices, mechanical calculating machines didn't arise until the late 1600s and weren't reliable for many years. It's unlikely that you'd be capable of building a mechanical computer until the industrial revolution. Note that Babbage was unsuccessful in building his machines even in the late 1800s.
If your goal is to build a Turing-complete machine of some sort, even if totally impractical, you could push the date back a lot. But that would be more of a curiosity than a useful computer.
Some semi-random examples
https://web.cecs.pdx.edu/~harry/Relay/
Main issue is memory. Takes a lot of space to make any usable about of memory out of relays.
I used to play that same thought experiment with more basic utilities like my toaster with it's various settings and electronic controllers. Then I was given a Dualit. No more philosophical dilemmas!
Kidding aside, it's always staggering how far removed we really are from operating on (humanly) first principles. Humbling.
But if you read those blogs you still notice the mind boggling height of the giants whose shoulders the bloggers stand on. Having access to simple chemicals like acids or various salts for example is huge. I wouldn't even know where to start if I had to bootstrap a highschool chemistry kit starting with nothing but my hands and my knowledge.
Note: Well, there are some quad transistor array chips, but that seems still in the same spirit.
At Basic Four Corporation I worked on systems built from 8"x11" circuit boards. A CPU might consist of two such cards joined on the front by a couple flat 50-pin cables and to the other components by a backplane.
Disk Controller: 1 board Terminal controller: 1 board etc
https://www.ricomputermuseum.org/collections-gallery/equipme...
Would be interesting to see some enterprising soul recreate a modern computer in such a form factor.
"Alan Kay gave me an Alto. That’s not the very last computer that I think is within my capability to understand everything that’s happening in there, but it’s getting near the end." https://mastersofscale.com/sam-altman-why-customer-love-is-a...
This is a visual representation of about what I understand about a processor and still outside of what I could actually make without a lot of reference material.
Inspired by this great submission, I was instead at http://visual6502.org/JSSim/index.html - 6502 simulator in HTML5 with visual changes on the virtual circuitry.
Purposedly better, faster, and has Z80, too.
For example - https://www.youtube.com/watch?v=Z5JC9Ve1sfI - It certainly makes for a cool background.
I'm interested in making (stochastic) algorithms fast, which always seems to eventually lead back to looking at code in compiler explorer. The extent of my knowledge there is basically "short assembly good, long assembly bad". But I've always lacked some "tactile" feeling (for lack of a better phrase) for what a register like "eax" or "rax" is. I hope that learning more about the megaprocessor might help get a glimpse of this.
The RAM size is of course the most limiting out of those three, but even if it were larger (and one could somehow build it without resorting to integrated circuits), you'd probably run into problems with the other fundamental limits if you wanted fancy things like memory in the order of megabytes.
Of course that's not the point, though, because building an entire general-purpose CPU from scratch at such a human-visible scale and from basic components is a feat in itself.
I'd seen this post before but I'd never noticed the monitor with the Windows login screen.
The Windows terminal is probably used to communicate with the megaprocessor.
