9.26 notes

Author: brownsarahm

_practice/2022-09-26.md

@@ -0,0 +1,11 @@
+1. add a hardware term to your group repo.  Remember to check other issues and then post an issue and self-assign it before you start working so that two people do not make the same one.  Review one other PR.
+1. Expand on your update to `abstraction.md`: Can you reconcile different ways you have seen memory before?
+1. Try understanding the max.hack and rect.hack. Make notes and answer the questions below in `assemblyexplore.md`.
+
+```
+1. Explain how max.hack works in detail.
+1. Write code in a high level language that would compile into this program. Try writing multiple different versions.
+1. What does this max.hack assume has happened that it doesn't include in its body.
+1. What does rect.hack do?  
+1. What did you learn trying to figure out how it works? 
+```

_prepare/2022-09-26.md

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+1. Bring questions about git to class on Wednesday.
+1. Your grading contract proposal is due Thursday at 3pm.
+1. Make sure that the `gh` CLI tool works by using it to create an issue called test on your kwl repo with `gh issue create`

_review/2022-09-26.md

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+1. Review and update your listing of how data moves through a program in your `abstraction.md`. Answer reflection questions.
+1. practice with the hardware simulator, try to understand its assembly language enough to modify it and walk through what other steps happen.
+1. Update your KWL chart with the new items and any learned items

_toc.yml

@@ -21,6 +21,7 @@ parts:
       - file: notes/2022-09-14
       - file: notes/2022-09-19
       - file: notes/2022-09-21
+      - file: notes/2022-09-26
   - caption: Activities
     chapters:
     - file: activities/kwl

notes/2022-09-26.md

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+# How do we study Computer Systems?
+
+## Admin
+
+- make sure you have a grading contract repo
+- you'll track your progress in your
+
+## Systems
+
+
+## Abstraction
+
+The advantage to assembly is that it is hardware independent and human readable. It is low level and limited to what the hardware *can* do, but it is a version of that that can be run on different hardware.
+```{warning}
+This is incomplete, will come back and fill in later
+```
+
+
+## Using the simulator
+
+On MacOS:
+
+```bash
+cd path/nand2tetris/tools
+bash CPUEmulator.sh
+```
+
+On Windows:
+Double click on the CPUEmulator.bat file
+
+
+We're going to use the test cases from the book's project 5:
+
+1. Load Program
+1. Navigate to nand2tetris/projects/05
+
+We're not going to *do* project 5, which is to build a CPU, but instead to use the test.
+
+For more on how the emulator works see the [CPU Emulator Tutorial](https://www.nand2tetris.org/_files/ugd/44046b_24b3a15aa628404fbf6dacd86d7da3af.pdf).
+
+For much more detail about how this all works [chapter 4](https://www.nand2tetris.org/_files/ugd/44046b_d70026d8c1424487a451eaba3e372132.pdf) of the related text book has description of the machine code and assembly language.
+
+
+## How does the computer actually add constants?
+
+We'll use add.hack first.  
+
+This program adds constants, 2+3.  
+
+It is a program, assembly code that we are loading to the simulator's ROM, which is memory that gets read only by the CPU.  
+
+Run the simulator and watch what each line of the program does.  
+
+Notice the following:
+- to compute with a constant, that number only exists in ROM in the instructions
+- to write a value to memory the address register first has to be pointed to what where in the memory the value will go, then the value can be sent there
+
+
+The simulator has a few key parts:
+- address register
+- program counter
+
+If you prefer to read, see [section 5.2.1- 5.2.6 of nan2tetris book](https://www.nand2tetris.org/_files/ugd/44046b_b2cad2eea33847869b86c541683551a7.pdf)
+
+- This program the first instruction puts 2 in the address register from the instructions in ROM.  
+- Then it moves the 2 through the ALU to the data register (D)
+- then it puts 3 on the address register
+- then it adds the numbers at D and A
+- then it puts 0 on the address register
+- then it write the output from the ALU (D) to memory (at the location indicated by the A register)
+
+```{admonition} Try if yourself
+- What line do you change to change where it outputs the data?
+- How could you add a third number?
+- How could you add two pairs, saving the intermediate numbers?
+- How could you do (4+4)*(3+2)?
+```
+
+
+
+
+## Hardware Overview
+
+
+```{important}
+Today is the first day outside of the grade free zone.
+```
+
+## Review today's class
+(required for a C or better)
+
+```{include} ../_review/2022-09-26.md
+```
+
+## Prepare for Next Class
+(required for a C or better)
+
+
+```{include} ../_practice/2022-09-26.md
+```
+
+```{warning}
+the template contracts in the repo have an error in them; use the ones on the [course website](https://introcompsys.github.io/fall2022/syllabus/contract.html).
+```
+
+## More Practice
+
+(mostly required for a B or better)
+
+```{include} ../_practice/2022-09-26.md
+```
+
+
+
+## Questions After Class
+
+• more about the hardware architecture abstractions
+
+• When requesting a review for a PR or something similar, would the only thing to do be attaching either you the professor or the teachers assistant?
+With our collaborative repo, would we facilitate the merges and reviews or would you need to have the last review of the information?
+Should we assume that when you ask to write a document, we should create a markdown file with a similar name (as opposed to an assignment with the description "add branches.md to your KWL repo")
+
+• Are there other simulators that we can play with?
+
+• for my grading contract if i choose to go for an A and stick with the A but don't meet the requirements how much is my grade affected
+
+• how the CPU performs addition and stores the result in a memory location on the RAM
+
+• Explain more levels of abstraction and how they are connected