The words spoken in the Unit 2 video, scene by scene, as its captions show them, with what the animations show marked [On screen: ...] where they play. Each speaker is named where the speaker changes. The Unit 2 reading covers the same material.
The narration is spoken by synthetic voices made for this course, each shown on screen as a drawn robot. No person is speaking.
Unit 2 — Ada's ordered procedure
Narrator: In 1843 a scientific journal in London published a translation from the French: an account of a calculating machine that did not exist.
The Analytical Engine
The machine was Charles Babbage's Analytical Engine, a design he had been working on for years and would never finish. On the screen is his general plan of it, Plan 25, dated the sixth of August 1840.
1843
The account of it was written by Luigi Menabrea, after Babbage presented the engine at meetings in Turin. The translator was Ada Lovelace, and she did not stop at translating. Appended to the translation were seven notes of her own, labelled A to G, running much longer than Menabrea's article they are attached to. The last, Note G, sets out how the engine could compute a sequence called the Bernoulli numbers. Those are the subject of Unit 6. What matters today is the form of what she wrote, not the mathematics inside it.
The machine did not exist
The engine was never completed, so nothing in Note G was ever run on the machine it was written for. The procedure had to be exact, with no chance to run it and catch mistakes.
Note G contains a table
Inside Note G's prose there is a table. Not a description of a method, not an argument that the method would work in principle — a table, with one line per operation, laid out in order, from the first thing the machine does to the last.
[On screen: The printed 1843 Note G diagram (facsimile, [P2a]). Its header row is lifted out and enlarged, and each column heading is named in turn: number of operation, which step and in what order; nature of operation, which operation; variables acted upon, what it reads; variables receiving results, what it writes; indication of change, what changes in the store; and statement of results, what the result should be. The closing line says every operation states which step it is, what it reads, what it writes and what its result should be, so every line can be checked on its own.]
Each line has its step number and names the operation to be performed. It says which of the engine's storage columns it takes its inputs from, and which column receives the result. Then which columns change, and what the result should be, written as a formula. So every line can be checked on its own: read the inputs, do the operation, and compare with what the table says should come out.
Each line is a state change
[On screen: Headed 'Explicit state change'. A table on the left, headed 'Illustrative lines, not from Note G', shows two lines; line 1 is selected: multiply V1 and V2 and write the result to V3. Line 2, dimmed, adds V3 and V4 into V4. On the right the store is shown before and after line 1. Before, V1 holds 2, V2 holds 3, V3 holds 0 and V4 holds 10. V1 and V2 are highlighted as the inputs read; after the operation V3 has changed from 0 to 6, while V1 (2), V2 (3) and V4 (10) are marked unchanged. A closing note says only the destination, V3, changes; nothing else was told to change.]
Hold on to that structure, because it is the whole unit. Each line is a change of state, written down. The storage columns here are named V-one to V-four. Before the line, the machine holds one set of values. The operation happens. After the line, it holds a different set. Nothing else changes, because nothing else was told to change.
Store and mill
Babbage's design kept two things physically apart: where numbers are held, and where arithmetic is done.
[On screen: Two boxes are drawn apart, with the gap between them marked 'physically apart'. On the left is the store, holding four columns, V1 = 2, V2 = 3, V3 = 0 and V4 = 10; it is labelled memory. On the right is the mill, labelled operations. The value 2 travels from V1 across the gap to the mill, then the value 3 from V2. In the mill the multiplication happens: 2 times 3 equals 6. Below them a two-line procedure appears, labelled illustrative lines, not from Note G: line 1, V1 times V2 into V3, which is selected, and line 2, V3 plus V4 into V4. The 6 travels back across the gap into the store, and V3 changes from 0 to 6. V4 is marked untouched, and line 2 is marked next, in order. These are illustrative values, the same as in the state-change animation.]
A store held numbers in columns; a mill did arithmetic on numbers brought to it from the store. Memory in one place, operations in another, and a procedure saying which numbers travel between them and in what order. That division turned out to be a durable idea.
Determinism
Three properties make this a procedure rather than an explanation. The first is determinism. Given the same starting values and the same sequence of operations, you get the same result. Every time. Not usually, not with high probability — every time. If you ran it twice and got different answers, that would not be a variation, it would be a fault.
Explicit state
The second is explicit state. Every number the procedure uses lives in a named place, and either a stated starting value or an earlier line put it there. There is no quantity that is simply understood to be available. If a value is needed and was not stated at the start, some line had to produce it, and you can point at that line.
Control flow
[On screen: On the left, under the label 'Illustrative lines, not from Note G', two lines of a procedure: line 1, V1 times V2 into V3, and line 2, V3 plus V4 into V4. On the right, the store starts with V1 = 2, V2 = 3, V3 = 0 and V4 = 10. Run in order, line 1 then line 2: V3 becomes 6, then V4 becomes 6 plus 10, 16. The two lines then swap places and run again from the same start: line 2 first writes 0 plus 10, so V4 stays 10, then line 1 makes V3 6. The two end states are side by side and differ at V4, 16 against 10, marked 'different end state'; a caption says that swapping two lines gives a different procedure. The store then clears, the lines return to their order and an arrow shows them running top to bottom. Line 2 is then bracketed as a group with a loop arrow labelled 'repeat', and a caption says Note G marks out a group of operations to be repeated (Lovelace 1843, Note G). A table on the right shows that how many passes the group makes depends on which value is wanted: for the first value one pass, V4 ends at 16; for the second, two passes, 22; for the third, three passes, 28, with a pass counter ticking beside the bracket. The closing line says one procedure with a controlled repetition gives a family of answers, not one.]
The third is control flow. The order is part of the meaning. Swap two lines and you have a different procedure, not the same procedure written differently. And the order is not always a straight run from top to bottom — Note G marks out a group of operations to be repeated, the number of repetitions depending on which Bernoulli number you want. On the screen, an illustrative line repeats once, twice or three times, and each count ends with a different value in V-four. That is the difference between a worked trace of one answer and a procedure that works for a family of them.
"The first program"
Now, the claim you will have heard about this document: that Note G is the first computer program, and Ada Lovelace the first programmer. This needs care here, because the claim is useful and it is also more complicated than a slogan.
Firm ground
What is on firm ground: the notes were published in 1843, signed with her initials, and Note G contains that ordered table for computing Bernoulli numbers. Those facts do not by themselves show that she was first.
Contested
What is genuinely debated starts from a fact. Babbage had already written sequences of operations for the engine, in his own unpublished notebooks. He never published them, and Note G was published. So whether Note G counts as "first" depends on whether publication is what "first" should mean. Historians also disagree about how the work on Note G was divided between the two of them. And the word "program" is a modern description, so applying it backwards is our decision, not theirs. The course's historical notes lay out what the sources actually support. Where they do not support a firm answer, the material says so instead of picking one.
"The Analytical Engine has no pretensions whatever to originate any thing."
There is one more thing, and it is why this unit exists at the start of a course about AI. Writing about what the engine could and could not do, Lovelace said this. Quote: "The Analytical Engine has no pretensions whatever to originate any thing." Note G, 1843.
Fully checkable
Read in context, it is a claim about following orders: the machine can carry out a procedure, and carrying out a procedure is not the same as producing something new. Whether that sentence still applies to the machines we have now is a real question, and Unit 17 comes back to it properly. But notice what it takes for granted: that you can say precisely what a machine was ordered to do, and check whether it did that. Note G is fully checkable. Every line is written down, and any line can be wrong in a way you can find.
Checker: The lab runs this table in exact fractions. With every line as intended, it gives the documented value, the number Note G sets out to compute. As printed, operation four divides the wrong way round, and with that line as printed the result is different. Unit 16 comes back to it.
Your turn
Narrator: Unit 3 looks at a system whose answers expose no step-by-step trace like this one. Before you go there, do the activity: take something you do without thinking, and write it down the way Ada had to.
Closing, 20 seconds, no speech. A candidate record on the left, a check against an independent reference in the middle, and a bracketed claim on the right fade in side by side. Below them: Continue with the course material, ai.qyber.dev/edu-ai-literacy-ada-verification/, Course playlist: youtube.com/playlist?list=PLPsBWTfgvakM, All links are also in the description, and Keep your record. Check the next claim.