The grace of human civilisation lies in two things: legal sciences and technical sciences. And while the legal progress is straight-forward and dependent, the technical one has its own pace and tasks greatly on the ability of techno man to independently produce results.
The State of Affaires at Primeval
Living in Primeval World a man have a constant need for shelter and to keep things up. Both needs can be solved by a techno man. Though he still cannot: he doesn't know the recipe for glue, which is essential for joining the wood. Even more he hasn't wieldy saw and other carpenter's tools, if any, so cannot work the wood.
Usual technical task in this age looks like "Will this sh-t of wood fall down when rain falls?" Which is technical, nevertheless. If you think inverse, consider lack of Laws of Nature in use.
Beside these is low-tech: cooking and accounting. Accounting is not done at all, and cooking is hurt by not having clocks. Any. Clocks.
High-tech is shipbuilding and carriage-building, if there any.
The Glorious Middle Age
The difficulties of Primeval persist, but who is able to first make plate — is the Freaking God of the War. Most of the tools, we know know, are in place, beside electronic, of course. So if you have a hunch how to join wood, taking past example, you will certaintly make the abovementioned high-tech: carriages and ships.
The low-tech gets bump with the invention of water and sand clock. Accounting books start first to encounter in this period. Though parchment is expensive, ink is mediocre, but the parchment can be erased by the tools of the age. Less expensive papyrus can be written too.
The high-tech is clockworking. There are need for clocks everywhere, in every even small town. Clocks and cloth are traded from the West, spices from the East.
The Golden Age
God said, Let Newton be! — and all was light. ~ Alexander Pope
The Greatest Techo Age has just arrived. Armed with Newton's Laws, paper for blueprints, and Differential Calculus, which is too invented by Newton, a techno man could produce almost every marvel to the human's eye.
It is hard, but it doesn't take others man's work to it. Else actual production. Of course you need the tools, they are not cheap, but affordable.
When it comes to high-tech it's the building. Masonry building, to be exact. Nothing supernatural, which a man of the age cannot do.
The paper and tower clocks makes the way for low-tech: mass recipe books appears, as well as accounting ones.
There's nothing stopping the fly of human's thought, else the ideas uninvented. You can furnish your mansion with the all tools of the age if you have money and want to use them.
The Fall of Industrial Age
Typewriter! Typewriter! Typewriter!
It's the sign of the age. First, it's a portable and fast printing machine. Second, and more importantly, no one can produce a typewriter on his own.
The skills required: fine metalworking, fine metal casting, glassmaking (for keys,) tinworking, engineering with blueprints, Ok you will buy the damn paper and metal.
As there's not enough, the electricity appears at second half of the age. And first have seen the automata: first automata is the sewing machine.
Programmers rise to fil the gap: for millenias you hadn't to have programming skills to do the job, with occasional exception of commanding techno men, and now it is a job on its own. Though the word "Programmer" is to be born later. They constitute the high-tech, and will remain through the next age.
The low-tech gets another bump with inventing the most cooking techniques and ingredients, and the birth of scientific approved bureaucracy makes the accounting a science.
JFYI AFIAK I hate it, though enjoy all the benefits of therefore.
You can write a program. Ok. Who to compile? A compiler who SUPRISE! automatically leaves the loopholes in executable code? Probably yes, if you haven't written your own. Which must run on OS such as Windows having innermost loopholes Petya/WannaCry exploited, or Linux, which has the most code in kernel and drivers hidden with no source code present.
I just hope my hammer hasn't electronic pinches to break it when the time or a circumstance comes.
The high-tech is such a crazy cyberpunk world is the projects (I will talk it below) to duplicate the existing tech. It has started from innocent-looking steel recipes from past age, who was sought, espionaged, and duped by every large World body. All because they are so important to objects to function.
The cooking is here with pro-graded cuisine: oven/stove that counts Joules, microwave oven with a grill and steamer, various machines to produce exact shapes and even blender to smoothie. Accounting is shifted heavily to project- and international finances-running. The specialist of the age can estimates the time&cost to cook eggs on Bermuda Islands and deliver them to afternoon. What is surprising, is that not so mundane things are estimated as well.