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As of 2020 leading makers of the most important fab photolithography equipment.

ASML: TSMC's Critical Supplier by Asianometry (2021)

Source.

Video 2.

How ASML Won Lithography by Asianometry (2021)

Source.

First there were dominant Elmer and Geophysics Corporation of America dominating the market.

Then a Japanese government project managed to make Nikon and Canon Inc. catch up, and in 1989, when Ciro Santilli was born, they had 70% of the market.

youtu.be/SB8qIO6Ti_M?t=240 In 1995, ASML had reached 25% market share. Then it managed the folloging faster than the others:

TwinScan, reached 50% market share in 2002
Immersion litography
EUV. There was a big split between EUV vs particle beams, and ASML bet on EUV and EUV won.
youtu.be/SB8qIO6Ti_M?t=459 they have an insane number of software engineers working on software for the machine, which is insanely complex. They are big on UML.
youtu.be/SB8qIO6Ti_M?t=634 they use ZEISS optics, don't develop their own. More precisely, the majority owned subsidiary Carl Zeiss SMT.
youtu.be/SB8qIO6Ti_M?t=703 IMEC collaborations worked well. Notably the ASML/Philips/ZEISS trinity

www.youtube.com/watch?v=XLNsYecX_2Q ASML: Chip making goes vacuum with EUV (2009) Self promotional video, some good shots of their buildings.

Photomask by

Ciro Santilli 40 Updated 2025-07-16

Asianometry by

Ciro Santilli 40 Updated 2025-07-16

www.youtube.com/channel/UC1LpsuAUaKoMzzJSEt5WImw

Very good channel to learn some basics of semiconductor device fabrication!

Focuses mostly on the semiconductor industry.

youtu.be/aL_kzMlqgt4?t=661 from Video "SMIC, Explained by Asianometry (2021)" from mentions he is of Chinese ascent, ancestors from Ningbo. Earlier in the same video he mentions he worked on some startups. He doesn't appear to speak perfect Mandarin Chinese anymore though based on pronounciation of Chinese names.

asianometry.substack.com/ gives an abbreviated name "Jon Y".

Reflecting on Asianometry in 2022 by Asianometry (2022)

Source. Mentions his insane work schedule: 4 hours research in the morning, then day job, then editing and uploading until midnight. Appears to be based in Taipei. Two videos a week. So even at the current 400k subs, he still can't make a living.

Web crawling by

Ciro Santilli 40 Updated 2025-07-16

Integrated circuit by

Ciro Santilli 40 Updated 2025-08-08

It is quite amazing to read through books such as The Supermen: The Story of Seymour Cray by Charles J. Murray (1997), as it makes you notice that earlier CPUs (all before the 70's) were not made with integrated circuits, but rather smaller pieces glued up on PCBs! E.g. the arithmetic logic unit was actually a discrete component at one point.

The reason for this can also be understood quite clearly by reading books such as Robert Noyce: The Man Behind the Microchip by Leslie Berlin (2006). The first integrated circuits were just too small for this. It was initially unimaginable that a CPU would fit in a single chip! Even just having a very small number of components on a chip was already revolutionary and enough to kick-start the industry. Just imagine how much money any level of integration saved in those early days for production, e.g. as opposed to manually soldering point-to-point constructions. Also the reliability, size an weight gains were amazing. In particular for military and spacial applications originally.

A briefing on semiconductors by Fairchild Semiconductor (1967)

Source.

Uploaded by the Computer History Museum. There is value in tutorials written by early pioneers of the field, this is pure gold.

Shows:

photomasks
silicon ingots and wafer processing

Scientific software by

Ciro Santilli 40 Updated 2025-07-16

System on a chip by

Ciro Santilli 40 Updated 2025-07-16

Ciro Santilli 40 Updated 2025-07-16

The only two truly relevant RTL languages as of 2020 are: Verilog and VHDL. Everything else compiles to those, because that's all that EDA vendors support.

Much like a C compiler abstracts away the CPU assembly to:

increase portability across ISAs
do optimizations that programmers can't feasibly do without going crazy

Compilers for RTL languages such as Verilog and VHDL abstract away the details of the specific semiconductor technology used for those exact same reasons.

The compilers essentially compile the RTL languages into a standard cell library.

Examples of companies that work at this level include:

Intel. Intel also has semiconductor fabrication plants however.
Arm which does not have fabs, and is therefore called a "fabless" company.

SymPy by

Ciro Santilli 40 Updated 2025-07-16

This is the dream cheating software every student should know about.

It also has serious applications obviously. www.sympy.org/scipy-2017-codegen-tutorial/ mentions code generation capabilities, which sounds super cool!

The code in this section was tested on sympy==1.8 and Python 3.9.5.

Let's start with some basics. fractions:

from sympy import *
sympify(2)/3 + sympify(1)/2

outputs:

7/6

Note that this is an exact value, it does not get converted to floating-point numbers where precision could be lost!

We can also do everything with symbols:

from sympy import *
x, y = symbols('x y')
expr = x/3 + y/2
print(expr)

outputs:

x/3 + y/2

We can now evaluate that expression object at any time:

expr.subs({x: 1, y: 2})

outputs:

4/3

How about a square root?

x = sqrt(2)
print(x)

outputs:

sqrt(2)

so we understand that the value was kept without simplification. And of course:

sqrt(2)**2

outputs 2. Also:

sqrt(-1)

outputs:

I is the imaginary unit. We can use that symbol directly as well, e.g.:

I*I

gives:

-1

Let's do some trigonometry:

cos(pi)

gives:

-1

and:

cos(pi/4)

gives:

sqrt(2)/2

The exponential also works:

exp(I*pi)

gives;

-1

Now for some calculus. To find the derivative of the natural logarithm:

from sympy import *
x = symbols('x')
print(diff(ln(x), x))

outputs:

1/x

Just read that. One over x. Beauty. And now for some integration:

print(integrate(1/x, x))

outputs:

log(x)

OK.

Let's do some more. Let's solve a simple differential equation:

y''(t) - 2y'(t) + y(t) = sin(t)

Doing:

from sympy import *
x = symbols('x')
f, g = symbols('f g', cls=Function)
diffeq = Eq(f(x).diff(x, x) - 2*f(x).diff(x) + f(x), sin(x)**4)
print(dsolve(diffeq, f(x)))

outputs:

Eq(f(x), (C1 + C2*x)*exp(x) + cos(x)/2)

which means:

f (x) = C_{1} + C_{2} x e^{x} + cos (x) /2

(1)

To be fair though, it can't do anything crazy, it likely just goes over known patterns that it has solvers for, e.g. if we change it to:

diffeq = Eq(f(x).diff(x, x)**2 + f(x), 0)

it just blows up:

NotImplementedError: solve: Cannot solve f(x) + Derivative(f(x), (x, 2))**2

Sad.

Let's try some polynomial equations:

from sympy import *
x, a, b, c = symbols('x a b c d e f')
eq = Eq(a*x**2 + b*x + c, 0)
sol = solveset(eq, x)
print(sol)

which outputs:

FiniteSet(-b/(2*a) - sqrt(-4*a*c + b**2)/(2*a), -b/(2*a) + sqrt(-4*a*c + b**2)/(2*a))

which is a not amazingly nice version of the quadratic formula. Let's evaluate with some specific constants after the fact:

sol.subs({a: 1, b: 2, c: 3})

which outputs

FiniteSet(-1 + sqrt(2)*I, -1 - sqrt(2)*I)

Let's see if it handles the quartic equation:

x, a, b, c, d, e, f = symbols('x a b c d e f')
eq = Eq(e*x**4 + d*x**3 + c*x**2 + b*x + a, 0)
solveset(eq, x)

Something comes out. It takes up the entire terminal. Naughty. And now let's try to mess with it:

x, a, b, c, d, e, f = symbols('x a b c d e f')
eq = Eq(f*x**5 + e*x**4 + d*x**3 + c*x**2 + b*x + a, 0)
solveset(eq, x)

and this time it spits out something more magic:

ConditionSet(x, Eq(a + b*x + c*x**2 + d*x**3 + e*x**4 + f*x**5, 0), Complexes)

Oh well.

Let's try some linear algebra.

m = Matrix([[1, 2], [3, 4]])

Let's invert it:

m**-1

outputs:

Matrix([
[ -2,    1],
[3/2, -1/2]])

Microarchitecture by

Ciro Santilli 40 Updated 2025-07-16

Nobel Foundation by

Ciro Santilli 40 Updated 2025-07-16

Zero-based numbering by

Ciro Santilli 40 Updated 2025-07-16

x86 Paging Tutorial / Multi-level paging scheme numerical translation example by

Ciro Santilli 40 Updated 2025-07-16

Page directory given to process by the OS:

entry index   entry address      page table address  present
-----------   ----------------   ------------------  --------
0             CR3 + 0      * 4   0x10000             1
1             CR3 + 1      * 4                       0
2             CR3 + 2      * 4   0x80000             1
3             CR3 + 3      * 4                       0
...
2^10-1        CR3 + 2^10-1 * 4                       0

Page tables given to process by the OS at PT1 = 0x10000000 (0x10000 * 4K):

entry index   entry address      page address  present
-----------   ----------------   ------------  -------
0             PT1 + 0      * 4   0x00001       1
1             PT1 + 1      * 4                 0
2             PT1 + 2      * 4   0x0000D       1
...                                  ...
2^10-1        PT1 + 2^10-1 * 4   0x00005       1

Page tables given to process by the OS at PT2 = 0x80000000 (0x80000 * 4K):

entry index   entry address     page address  present
-----------   ---------------   ------------  ------------
0             PT2 + 0     * 4   0x0000A       1
1             PT2 + 1     * 4   0x0000C       1
2             PT2 + 2     * 4                 0
...
2^10-1        PT2 + 0x3FF * 4   0x00003       1

where PT1 and PT2: initial position of page table 1 and page table 2 for process 1 on RAM.

With that setup, the following translations would happen:

linear    10 10 12 split  physical
--------  --------------  ----------
00000001  000 000 001     00001001
00001001  000 001 001     page fault
003FF001  000 3FF 001     00005001
00400000  001 000 000     page fault
00800001  002 000 001     0000A001
00801004  002 001 004     0000C004
00802004  002 002 004     page fault
00B00001  003 000 000     page fault

Let's translate the linear address 0x00801004 step by step:

In binary the linear address is:

0    0    8    0    1    0    0    4
0000 0000 1000 0000 0001 0000 0000 0100

Grouping as 10 | 10 | 12 gives:

0000000010 0000000001 000000000100
0x2        0x1        0x4

which gives:

page directory entry = 0x2
page table     entry = 0x1
offset               = 0x4

So the hardware looks for entry 2 of the page directory.

The page directory table says that the page table is located at 0x80000 * 4K = 0x80000000. This is the first RAM access of the process.
Since the page table entry is 0x1, the hardware looks at entry 1 of the page table at 0x80000000, which tells it that the physical page is located at address 0x0000C * 4K = 0x0000C000. This is the second RAM access of the process.
Finally, the paging hardware adds the offset, and the final address is 0x0000C004.

Page faults occur if either a page directory entry or a page table entry is not present.

The Intel manual gives a picture of this translation process in the image "Linear-Address Translation to a 4-KByte Page using 32-Bit Paging": Figure 1. "x86 page translation process"

Figure 1.
x86 page translation process
.

x86 Paging Tutorial / Invalidating TLB entries by

Ciro Santilli 40 Updated 2025-07-16

When the process changes, cr3 change to point to the page table of the new current process.

This creates a problem: the TLB is now filled with a bunch of cached entries for the old process.

A simple and naive solution would be to completely invalidate the TLB whenever the cr3 changes.

However, this is would not be very efficient, because it often happens that we switch back to process 1 before process 2 has completely used up the entire TLB cache entries.

The solution for this is to use so called "Address Space Identifiers" (ASID) as mentioned in sources such as:

Basically, the OS assigns a different ASID for each process, and then TLB entries are automatically also tagged with that ASID. This way when the process makes an access, the TLB can determine if a hit is actually for the current process, or if it is an old address coincidence with another process.

The x86 also offers the invlpg instruction which explicitly invalidates a single TLB entry. Other architectures offer even more instructions to invalidated TLB entries, such as invalidating all entries on a given range.

x86 Paging Tutorial / Process memory layout by

Ciro Santilli 40 Updated 2025-07-16

For each process, the virtual address space looks like this:

------------------ 2^32 - 1
Stack (grows down)
v v v v v v v v v
------------------

(unmapped)

------------------ Maximum stack size.


(unmapped)


-------------------
mmap
-------------------


(unmapped)


-------------------
^^^^^^^^^^^^^^^^^^^
brk (grows up)
-------------------
BSS
-------------------
Data
-------------------
Text
-------------------

------------------- 0

The kernel maintains a list of pages that belong to each process, and synchronizes that with the paging.

If the program accesses memory that does not belong to it, the kernel handles a page-fault, and decides what to do:

if it is above the maximum stack size, allocate those pages to the process
otherwise, send a SIGSEGV to the process, which usually kills it

When an ELF file is loaded by the kernel to start a program with the exec system call, the kernel automatically registers text, data, BSS and stack for the program.

The brk and mmap areas can be modified by request of the program through the brk and mmap system calls. But the kernel can also deny the program those areas if there is not enough memory.

brk and mmap can be used to implement malloc, or the so called "heap".

mmap is also used to load dynamically loaded libraries into the program's memory so that it can access and run it.

Stack allocation: stackoverflow.com/questions/17671423/stack-allocation-for-process

Calculating exact addresses Things are complicated by:

Address Space Layout Randomization.
the fact that environment variables, CLI arguments, and some ELF header data take up initial stack space: unix.stackexchange.com/questions/145557/how-does-stack-allocation-work-in-linux/239323#239323

Why the text does not start at 0: stackoverflow.com/questions/14795164/why-do-linux-program-text-sections-start-at-0x0804800-and-stack-tops-start-at-0

x86 Paging Tutorial / ARM by

Ciro Santilli 40 Updated 2025-07-16

Information about ARM paging can be found at: cirosantilli.com/linux-kernel-module-cheat#arm-paging

1932 Nobel Prize in Physics by

Ciro Santilli 40 Updated 2025-07-16

To Ernest Lawrence for the cyclotron.

Classic RISC pipeline by

Ciro Santilli 40 Updated 2025-07-16

Robotics by

Ciro Santilli 40 Updated 2025-07-16

Tesla Dojo by

Ciro Santilli 40 Updated 2025-07-16

 Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.

Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!