Do Now · Lab Notebook · 10 minutes

Set up your notebook. You will need it at the end of class.

Terminology and Concepts to look out for

Copy these. Leave space under each one for a definition.

  • capacity
  • load
  • runtime
Relevance to Me

Think about these. Nothing to write.

  • Last week you learned three reasons a Chromebook cannot run the file. Which of the three is the one you had to hear twice?
  • Somebody asks you what an AI is. You have four sentences. Which four?
  • If you had a machine with room to spare, would that make the AI yours?
Question of the Day

Copy this into your Lab Notebook and leave room under it. You will answer it at the end of class.

What does the machine actually do when it runs a model?

Before the reading

The words, in plain terms

None of these are new words. They are the three anchors the twelve pictures land on. Capacity, load, runtime.

capacity
Whether a file will fit in a place that has a size.
Two numbers, one subtraction. The file has a size, every place it could sit has a size. Storage capacity, RAM capacity, VRAM capacity — same idea in three places.
In a gameThe install-size line in system requirements: what fits on the drive.
The ladder is capacity applied to four machines. Three cards hold 6.63 gigabytes; the Chromebook comes up short.
load
Copy, not move. The file stays in storage; a copy of it appears in VRAM.
Same file, two addresses. One of them forgets the moment the power is cut. The other holds through a power cut and a year. The wrong picture is on schematic 02b for exactly this reason.
In a game"Loading…" between a menu and a level. Nothing leaves the disc when the level loads; a copy of the level arrives in memory.
runtime
Software with real instructions in it, whose whole job is to open a file that has none.
In this room the runtime is LM Studio, with llama.cpp underneath. Without one, the file sits and does nothing. That is what the third failure is about.
In a gameA game engine like Unity or Unreal — the piece that reads the maps and runs the rules.
Where the Pictures Land

Two days ago the class opened a folder and saw a 6.63 gigabyte file that does nothing on its own. What has happened since is not more material. It is the same material seen twice, once through the shape of the hardware and once through the shape of the software. The twelve pictures the room worked from are three arcs, and today is the day to say what they were doing.

The first arc is capacity. A file has a size, and every place it could sit has a size, and those two numbers decide whether the file can be there. The first picture named the vocabulary: RAM and CPU in the machine, VRAM and GPU on the card, storage underneath both. Nothing on that picture is optional and nothing on it is decoration. Every word this unit uses is on it. The ladder that followed was the same picture applied to four real machines, and the arithmetic settled the question. Three cards in the world can hold 6.63 gigabytes and none of them is in this room.

The second arc is one sentence, and it is the sentence the room keeps missing. Load means copy, not move. When a machine loads the file it does not pick it up out of storage and carry it somewhere else. The file stays where it is, at full strength, and a copy of it appears in VRAM. Same file, two addresses. One of them forgets the moment the power is cut and the other one holds through a power cut, a drawer, and a year. The picture with the wrong drawing beside the right drawing is on the panel for exactly this reason. What the word load sounds like is the picture on the left, and it is wrong on purpose so the picture on the right has something to be correct against.

The third arc is the software stack, and it exists because a file that fits still does nothing. Numbers are not instructions. Something with real instructions has to open the file and read them. That something is called a runtime, and it does not stand alone. It sits inside the operating system, which sits inside the machine, and the file sits inside the runtime because the runtime is the only thing that can do anything with it. Four layers, and the picture claims that removing any one of them leaves nothing that answers.

The Chromebook fails at this layer for a reason that has nothing to do with numbers. ChromeOS will not permit a runtime to be installed. The picture of the software stack with one box empty is the third failure and it is different in kind from the other two. Storage was a number. RAM was a different number. This one is not a number at all. Not too small, not too slow, not allowed.

Three arcs, twelve pictures, one machine. A student who can name each arc can name what the machine actually does when it runs a model.

Work these together
10 questions on the passage. Pick an answer, then check it. Nothing here is collected.
Question 1 of 10the passage
According to the passage, what does the word capacity name in this unit?
Question 2 of 10the passage
The passage says load means copy, not move. What does that mean about the file in storage after the machine loads it?
Question 3 of 10the passage
The passage names the runtime as one of four layers in the software stack. What is a runtime?
Question 4 of 10the passage
The passage says three cards in the world can hold this file and none of them is in this room. Which pieces of last week’s arithmetic put that number at three?
Question 5 of 10the passage
Which picture is drawn wrong on purpose, and why?
Question 6 of 10the passage
According to the passage, why does taking any one layer out of the software stack leave nothing that answers?
Question 7 of 10the passage
The passage says the Chromebook’s third failure is different in kind from the first two. What makes it different?
Question 8 of 10the passage
Which sentence best states the shape of the unit so far?
Question 9 of 10the passage
The passage says every word this unit uses is on the first picture. Which set of words does it list?
Question 10 of 10the passage
A machine has forty gigabytes of storage free, eight gigabytes of VRAM, and no runtime installed. The file is 6.63 gigabytes. Based on the passage, what happens if the file is copied over?
The pictures
①
Inside the machine A machine contains two places that hold a file while it is worked on and two processors that do the work. RAM and CPU sit in the machine. VRAM and GPU sit on the card. Storage sits underneath both and holds the file at all times; RAM and VRAM hold copies of it while work is happening. IN THE MACHINE ON THE CARD The machine RAM holds the file while the CPU works on it VRAM holds the file while the GPU works on it CPU does work where each step waits on the one before it GPU does millions of small multiplications all at once Storage where the file stays, whether or not anything is using it. Nothing is ever worked on here. HOLDS IT WORKS ON IT KEEPS IT Holding and working are two different jobs. A file being worked on is in two places at once.
Inside the machine — RAM and CPU on the machine side, VRAM and GPU on the card, storage underneath both.
Read the picture

A machine has two of each, and the reason is that holding something and working on something are two different jobs.

Read the picture across, not down. The top row is the two places a file can sit while it is being used. The bottom row is the two things that can do the arithmetic. The left column is in the machine itself. The right column is on the card.

Storage runs underneath both columns because it belongs to neither. Nothing is ever worked on in storage. A file there is a file waiting.

The words in the boxes are the words you will see on a spec sheet, in a store, and in every guide about this you ever read.

②
The ladder All four machines together. A Chromebook with four gigabytes of RAM and no card, then three graphics cards carrying eight, sixteen and twenty four gigabytes of VRAM. The same 6.63 gigabyte file is laid into each. It overflows the Chromebook and fits the other three. The ladder One file. Four machines. One subtraction each. 6.63 4 GB 2.63 GB over the line Chromebook RAM. No card at all. Does not fit 6.63 8 GB RTX 4060 VRAM on the card Fits 6.63 16 GB RTX 5070 Ti VRAM on the card Fits 6.63 24 GB RTX 4090 VRAM on the card Fits The first bar is RAM in a machine. The other three are VRAM on a card. The Chromebook does not have a small card. It has none.
The ladder — all four machines together, with verdicts. This is the panel students copy.
Read the picture

Every bar is drawn to the same scale, and the red block is the same file every time. That is what makes the four comparisons honest.

The question is the same for each machine and it is answered with subtraction. Is the number on the machine larger than 6.63, or is it not.

The first bar is different from the other three, and the difference matters. The Chromebook’s bar is RAM, the working memory in the machine itself. The other three bars are VRAM, working memory on a card. The Chromebook does not have a small card. It has no card at all, which is why its RAM is the only thing that could possibly hold the file, and why it comes up short by 2.63 gigabytes.

Notice what the question never needed. Not the speed of the machine, not the year it was made, not the price. One subtraction settled all four.

Three machines in the world can hold this file. None of them is in this room.

③
What the word suggests, and what the machine does Two pictures of the same machine. The left one is deliberately wrong: an arrow carries the file up out of storage into VRAM, leaving an empty dashed outline behind. The right one is correct: no arrow, the file still in storage, and a second copy of it in VRAM. WHAT THE WORD SUGGESTS The machine VRAM the file, 6.63 GB Storage empty now The file left one place and arrived in another. Nothing about a computer works this way. WHAT THE MACHINE DOES The machine VRAM VOLATILE the file, 6.63 GB Storage NON-VOLATILE the file, 6.63 GB Storage still has it. VRAM has a second copy. No arrow, because nothing travelled. Load a truck and the crate leaves the warehouse. Load a file and the file stays exactly where it was.
What the word load sounds like, beside what the machine actually does. The left panel is drawn wrong on purpose.
Read the picture

Two pictures of the same machine.

The picture on the left is deliberately wrong. It shows what the word load sounds like: an arrow carries the file up out of storage into VRAM, and there is a dashed outline where the file used to be.

The picture on the right is what actually happens. The file stays in storage, at full strength. A copy of it appears in VRAM. Two addresses, one file, and one of them forgets when the power goes off.

Load means copy, not move. Placed here on purpose, in grey and dashed, so the correct picture beside it has something to be correct against.

④
A program and a model file Two files side by side. The program file contains readable instructions a machine can follow. The model file contains rows of numbers and no instructions at all. A PROGRAM THE MODEL FILE if answer is empty: ask again else: show the answer stop Instructions. Steps a machine can follow, in order, one after another. 0.0142 -0.9931 0.4408 -0.1176 -0.7725 0.0038 0.6621 0.2094 0.3310 -0.4457 -0.0089 0.8812 -0.2201 0.7736 0.1150 -0.6674 0.9084 -0.0512 0.3397 0.0261 -0.4419 0.6103 -0.8850 0.1928 ... and billions more No instructions anywhere in it. Nothing here can be followed. A machine can run the one on the left. Nothing can run the one on the right until something reads it.
Numbers, not instructions — a program (readable lines) beside the model file (rows of numbers).
Read the picture

Both sides are files. Only one of them is a program.

On the left are instructions: steps a machine can carry out, in order, one after another. You do not have to understand what the program does to see that it is telling something to do something.

On the right is the model file. There are no steps. There is no order. There is nothing to carry out. It is a record of numbers, billions of them, and a machine handed this file has been given no instructions at all.

That is why yesterday ended with a file that fits on three machines and does nothing on any of them. Fitting was never the last problem.

⑤
The software stack A machine contains an operating system, which contains a runtime, which holds the model file. Four layers, each inside the one above it. The machine Windows, macOS or Linux the runtime reads the numbers and does the arithmetic the file numbers, no instructions, 6.63 GB Four layers, each inside the one above it. Take any one away and nothing answers.
The software stack — the machine contains the OS, which contains the runtime, which holds the file. Four layers.
Read the picture

Four layers, each one sitting inside the one above it.

The machine is the hardware. The operating system is the software that starts when the power comes on and decides what else is allowed to run. The runtime is a real program, with real instructions in it, whose whole job is to open a file that has none. The file sits inside the runtime because the runtime is the only thing that can do anything with it.

Take any one layer away and nothing answers. That is worth testing on yourself: pick a layer, remove it, and say what breaks.

⑥
The Chromebook The same stack drawn again with the runtime box empty and outlined in dashes. The model file sits in storage inside the machine, perfectly intact, because there is nothing above it that can open it. The machine ChromeOS no runtime and no way to install one Nothing here to read the numbers. Storage the file, 6.63 GB The same picture, with one box empty. The file downloads fine and sits there like any other file. It just never gets copied up. Not too small. Not too slow. Not allowed.
The hole — the same stack with the runtime box empty. Chromebook. Not too small, not too slow, not allowed.
Read the picture

This is the same picture as the software stack, with one box empty. Compare them directly. The machine is the same size, the operating system region is the same size, and the runtime box is in exactly the same place.

What changed is that the box is empty and cannot be filled. ChromeOS does not permit software like LM Studio or llama.cpp to be installed on a school-managed device.

The file has moved outside the machine, because there is nothing in there that could open it.

This is the Chromebook’s third failure and it is different in kind from the other two. The first was storage, and deleting things would fix it. The second was RAM, and nothing you delete would help. This one is not about a number at all. Not too small, not too slow, not allowed.

Where the pictures land
The pictures are numbered on the left. Each question says which one it is about.
The words, in plain terms
capacity
Whether a file will fit in a place that has a size.
Two numbers, one subtraction. The file has a size, every place it could sit has a size. Storage capacity, RAM capacity, VRAM capacity — same idea in three places.
In a gameThe install-size line in system requirements: what fits on the drive.
The ladder is capacity applied to four machines. Three cards hold 6.63 gigabytes; the Chromebook comes up short.
load
Copy, not move. The file stays in storage; a copy of it appears in VRAM.
Same file, two addresses. One of them forgets the moment the power is cut. The other holds through a power cut and a year. The wrong picture is on schematic 02b for exactly this reason.
In a game"Loading…" between a menu and a level. Nothing leaves the disc when the level loads; a copy of the level arrives in memory.
runtime
Software with real instructions in it, whose whole job is to open a file that has none.
In this room the runtime is LM Studio, with llama.cpp underneath. Without one, the file sits and does nothing. That is what the third failure is about.
In a gameA game engine like Unity or Unreal — the piece that reads the maps and runs the rules.
①Start with a picture.
The vocabulary in one drawing. RAM and CPU on the machine side, VRAM and GPU on the card, storage underneath both. Every word today is on this picture.
②The ladder.
Three cards in the world can hold this file. None of them is in this room. The Chromebook has no card at all, which is why its RAM is the only candidate and why it comes up short by 2.63 gigabytes.
Ask

Which pair of numbers decides whether the machine on your desk can hold this file?

Reveal

VRAM on the card against the file size, or RAM in the machine against the file size when there is no card. Every other number is beside the point today.

③What load actually is.
The picture on the left is what the word load sounds like. The picture on the right is what the machine actually does. Drill this: the file does not move; a copy of it appears in VRAM. Same file, two addresses. One of them forgets.
Ask

After the machine loads the file, what is in storage?

Reveal

The same file, at full strength, exactly as before. Loading does not empty storage. It puts a copy of the file in VRAM while leaving the original where it is.

④The file is not a program.
Yesterday's bridge. Numbers on one side, instructions on the other. A machine can follow the instructions on the left. Nothing can follow the numbers on the right until something reads them. Fitting was never the last problem.
⑤The stack.
Four layers, and taking any one away leaves nothing that answers. The machine holds the operating system. The operating system holds the runtime. The runtime holds the file. The file sits inside the runtime because the runtime is the only thing that can do anything with it.
Ask

Pick a layer and remove it. What breaks?

Reveal

Remove the machine and there is nowhere for anything to run. Remove the operating system and no other software can be installed. Remove the runtime and the file has nothing to open it. Remove the file and there is no model to run. Every layer is load-bearing.

⑥The hole.
The same stack with one box empty. ChromeOS will not permit the runtime to be installed on a school-managed device. Not too small, not too slow, not allowed. This is the third failure and it is different in kind from the other two.
Ask

Could a student fix this by clearing storage or by adding RAM?

Reveal

No. Storage and RAM are numbers. This one is not about a number at all. The operating system decides what can be installed, and no amount of hardware changes that decision.

The rest of the block

Partner work first. Then quiet work time.

The three rules
  • No cellphones
  • No sleeping
  • No non-academic use of Chromebooks
What you get
  • A quiet room and music
  • No interruptions from the teacher
  • If you are caught up on this course's work, you may work on anything legitimate for another class
If you are picking, pick reading or writing.
Everything we build in this class, we build with words. The tools take writing as input. How well you write is the ceiling on what you can make them do.
Open this now: muggsofcompsci.net/decks/cs1-stack-day3-wedo
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