Aug 31, 2015

Data Structures for Andela: Iterators (part 2)

As part of Stack Overflow's pro-diversity initiatives, I have been helping Andela by mentoring one of their fellows, Bosun, in data structures and algorithms. In the Stack Overflow "default open" style, I am putting some of our notes on the internet, in the hope they will be useful to more people. Most of the code is either pseudo-code or JavaScript, which we chose because it's simple and easy to access and everyone pretty much knows the basics of it. Andela notes index Iterators (part 1) Iterat…

Aug 13, 2015

Announcing z80, my Zilog z80 emulator

The Zilog Z80 is an 8-bit microprocessor designed by Zilog and sold from July 1976 onwards. It was widely used both in desktop and embedded computer designs as well as for military purposes. The Z80 and its derivatives and clones made up one of the most commonly used CPU families of all time, and, along with the MOS Technology 6502 family, dominated the eight-bit microcomputer market from the late 1970s to the mid-1980s. z80 (zee-eighty) is an open source project I built in the past few months i…

Aug 10, 2015

A computer from scratch - Fish and chips

In the first installment of "A computer from scratch", I've built a NAND gate. I've also introduced the my "scaling" rule: if I build something, I can buy it pre-made, because I only have one lifetime to spend on this :-) Therefore. I've bought a bunch of 4011 CMOS NAND gates, here they are: And here's what they do: With this in mind, and with the diagrams in my second installment, I proceeded with building NOT, AND and OR gates. Of course this wasn't without confusion and questions, but fortuna…

Aug 05, 2015

Data Structures for Andela: Iterators (part 1)

As part of Stack Overflow's pro-diversity initiatives, I have been helping Andela by mentoring one of their fellows, Bosun, in data structures and algorithms. In the Stack Overflow "default open" style, I am putting some of our notes on the internet, in the hope they will be useful to more people. Most of the code is either pseudo-code or JavaScript, which we chose because it's simple and easy to access and everyone pretty much knows the basics of it. Andela notes index Iterators (part 1) Iterat…

Jul 31, 2015

The one mistake that ultimately destroys modern companies

Openly inspired by a nice talk by Joel Spolsky London, 1850. Let's say you are the owner of a factory that produces nails and bolts. Workers use huge, expensive machinery in a large factory. Machinery is so expensive you needed a lot of money to buy it, so it's paramount to use it as much as possible. On the other hand, the machinery is great. It allows you to hire people with low skills, because it makes perfect pieces without the need of true artisans of yonder. All the pieces are the same, no…

Jul 26, 2015

A computer from scratch - NANDing all the way

A technical side note to my first "A computer from scratch" post and In preparation for the next step, I've examined whether it's possible to build any gate from NANDs. Is it possible? YES! Let's prove it, mathematically. Theorem Any truth table can be built by combining NANDs. Lemma 1 Any truth table can be built with OR, AND and NOT. Proof Any truth table is defined by N bits in input (i1, i2, …, ik, …, iN). A truth table will also have 2N outputs (out1, out2, …, outl, …, out2N). We want to cr…

Jul 20, 2015

A computer from scratch - Eating at NANDos

I am attempting to build a computer from prime principles. Am I crazy? Probably. But I have a plan. Let's start from the beginning Why, oh why? Because not knowing how stuff works bugs me to no end. It's not enough for me to use a programming language. In the past I dabbled and spent more than a little time playing with lower level stuff like assembly. I also spent considerable time thinking architecturally about systems -- in fact I have been a senior software architect (whatever that means, lo…

Jun 24, 2015

My talks this year

There are three conferences I'll be speaking at this year. I'm seriously trying to do as few conferences as possible, but I really wanted to speak at these. If you'd like to chat about code and development, drink a beer or eat a pizza: I'm game. Here's the amazing 3: jDay my bio page JDay is one of largest web development conferences in Ukraine (if not the best conference). It's in held in Lviv and last year I had promised to attend but could not make it. So I'm there this year and hopefully it …

Jun 19, 2015

Agile development and pluralistic management: why Scrum fails

The Scrum methodology is often introduced because developers want it. On paper, it empowers them—if applied correctly—and developers need decision-making empowerment because development is a creative endeavor. Of all the different types of people I've known, hackers and painters are among the most alike. What hackers and painters have in common is that they're both makers. Along with composers, architects, and writers, what hackers and painters are trying to do is make good things. —Paul Graham …

Mar 09, 2015

Stack Overflow: answer sources by the numbers

I spent the past few weeks taking an in-depth look at how our users find questions to answer, with a keen eye on Stack Overflow. I measured user behavior and click streams and discussed with the other Stack Overflow developers and community managers how they meant the navigation and questiion list pages to work when they implemented them. Last week I blogged about the answer sources. This posts deal with the measured user behavior. Where do our users actually find stuff to answer? What do the nu…

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