Hieu's Blog

Load pubkey "/root/.ssh/key.pem": invalid format

| 2 minutes | 282 words | Hieu Le

Last week, i tackled a task that required to ssh to remote server from a cron job. Identity is authenticated using PEM file. I can connect successfully from my local terminal with command. $ ssh -i ~/.ssh/key.pem root@host My PEM file format is as such -----BEGIN RSA PRIVATE KEY----- [actual key] -----END RSA PRIVATE KEY----- The problem happened when cron job (running within a docker container) try to ssh, there is Load pubkey “/root/. [Read More]

ssh docker

Without CS degree

Learn on my own

| 2 minutes | 337 words | Hieu Le

I don’t have a CS degree so I’ve had to learn on my own. (@RandallKanna) This is the title of a twitter thread which is true for me. I found this thread a world of useful resources that a blog post to document them for later use is a good idea. Below are the original post and the links to the courses/material/videos. Start with a great intro course to get you excited about learning. [Read More]

course CS book twitter self-taught learn resource

Nand2tetris W5

Computer architecture

| 3 minutes | 630 words | Hieu Le

Last week, my wife came to BKK to see me and we had a wonderful short trip to Koh Lan island just 40 minutes away from Pattaya. It had been almost 2 months since we last met when i was in Vietnam back then, so that we did enjoyed our time together. Moreover, we accompanied 2 great friends in Son and Tik and all four of us took photos, shared stories and laughed so hard in that sea food restaurant while playing Tik-guessing game and drinking beers. [Read More]

learn course nand computer architecture Neumann CPU

Nand2tetris W4

Machine Language Programming

| 3 minutes | 534 words | Hieu Le

Background Every hardware platform is designed to execute commands in a certain machine language, expressed using agreed-upon binary codes. Writing programs directly in binary code is a possible, yet unnecessary. Instead, we can write such programs using a low-level symbolic language, called assembly, and have them translated into binary code by a program called assembler. Machine Language After making the gates and chips in previous 3 weeks, i had a chance to learn more about the machine language which is in binary form. [Read More]

learn course nand assembly I/O register

Nand2tetris Week3

Memory & Hello Time

| 2 minutes | 374 words | Hieu Le

Background The computer’s main memory, also called Random Access Memory, or RAM, is an addressable sequence of n-bit registers, each designed to hold an n-bit value. In this project you will gradually build a RAM unit. This involves two main issues: (i) how to use gate logic to store bits persistently, over time, and (ii) how to use gate logic to locate (“address”) the memory register on which we wish to operate. [Read More]

learn course nand logic gate RAM memory

Nand2tetris Week2

Boolean Arithmetic - Toughest challenge so far

| 2 minutes | 400 words | Hieu Le

Background The centerpiece of the computer’s architecture is the CPU, or Central Processing Unit, and the centerpiece of the CPU is the ALU, or Arithmetic-Logic Unit. In this project you will gradually build a set of chips, culminating in the construction of the ALU chip of the Hack computer. All the chips built in this project are standard, except for the ALU itself, which differs from one computer architecture to another. [Read More]

learn course nand logic gate ALU binary

Nand2tetris Intro

Build a Modern Computer from First Principles

| 1 minutes | 3 words | Hieu Le

Course Intro. Excited?

learn course nand

Nand2tetris Week1

Primitive Nand gate

| 2 minutes | 311 words | Hieu Le

Background A typical computer architecture is based on a set of elementary logic gates like And, Or, Mux, etc., as well as their bit-wise versions And16, Or16, Mux16, etc. (assuming a 16-bit machine). This project engages you in the construction of a typical set of basic logic gates. These gates form the elementary building blocks from which more complex chips will be later constructed. Here is what i have learnt in this week. [Read More]

learn course nand logic gate

Vim Editor

| 3 minutes | 470 words | Hieu Le

Well, recently i often work with docker and control config on server, i suffered a lot due to my weakness regards vim usage on linux. Turn out, these basic things prove significant as you’d like to pursue DevOps career. It would be great to improve on my vim skill by taking note down the essential of this powerful editor. Moreover, there is one tutor right in your Ubuntu terminal. Let’s get started and hope you learn something. [Read More]

vim linux