05 Sunday May 2019
Posted in CS101
Tags
finite state machine, FSA, FSM, full adder, half adder, Python, state engine, state table, truth table
I was involved in a debate recently about whether a full adder logic circuit is a computer. The computer science answer is: “No, not as we define a computer.”
I plan to address that answer in detail on my main blog. Here I wanted to show some of the different ways a full adder can be modeled and implemented.
19 Monday Dec 2016
Posted in CS101
Tags
computer language, computer languages, computer programming, computer science, GOTO statement, iteration, language design, loop statements, programming language, recursion
When it comes to what makes a computer (or any other) language a programming language, there are three characteristics usually required:
This post is just a brief note (for a friend) about the third item and why it allows three distinct options.
16 Tuesday Aug 2016
Posted in CS101
Tags
constants, defined values, global constants, literal values, literals, named constants, named values, numerical constants, P.J. Plauger, string constants
Along with “always use less-than” is another great piece of always advice, except this one is a prohibition, a never rather than an always (same thing, really, from a programmer’s point of view).
It has to do with never having literal values embedded in your code!
08 Monday Aug 2016
Posted in CS101
In his brief 1982 essay (EWD831), computer science giant Edsger Dijkstra examines a topic that (inappropriately, as it turns out) vexes some programmers: Why in the world do computer people count starting at zero? Everyone knows that counting starts at one!
As it turns out, there are two very good reasons for counting from zero!
06 Saturday Aug 2016
Posted in CS101
Tags
computer language, computer languages, computer programming, computer science, language design, programming language, Turing complete
Back in the post HTML is not a programming language! I brought up the three properties required by a programming language. A discussion recently got me thinking about it again. This post is just some notes on those thoughts…
25 Wednesday Nov 2015
Posted in CS101
Tags
computer, computer code, computer programming, computer science, Python code, state engine, state table
In the first two parts of this series I’ve introduced state engines and taken apart a specific instance of an engine. Now it’s time to tie together the design idea with approaches to building a variety of such engines.
Because the programming logic is in the state table, the engine can be fairly generic. That means it’s possible to create a state engine framework you can reuse for a variety of applications.
11 Wednesday Nov 2015
Posted in CS101
Tags
computer, computer code, computer programming, computer science, Python code, state engine, state table
Last time I introduced state engines and state tables. I showed parts of a simple implementation of one in Python. It parsed the language introduced in Little Programming Languages. This post continues that, so be sure you’ve read that first article.
I got as far as the state table implementing the process, and that’s where this post picks up. I’ll also get into the SourceReader class that does the heavy lifting.
08 Sunday Nov 2015
Posted in CS101
At one point in my career, the state engine (SE) was one of my favorite AWK hammers. At the time much of the work involved text processing or, in some cases, serial byte processing (which is not quite the same thing). That sort of thing is right in the wheelhouse for a state engine.
They are a very useful tool and an important part of any programmer’s toolkit.
05 Monday Oct 2015
Posted in CS101
Tags
computer code, computer programmers, computer programming, programming language, real programmers, software development
There is a common tendency, as we crank out code, to think that we’ll come back later and write some really good comments — comments that future reviewers will view with admiration for their clarity, completeness, and humor. But if we’re honest we have to admit: Later never comes. We never go back and write those great comments. Often we don’t write any comments at all other than some placeholder we might dash off at the time.
Which is why Rule #4: Comment As You Go!
22 Monday Dec 2014
Posted in CS101
Tags
computer code, computer language, computer languages, CSS, data, data type, HTML, Java, JavaScript, programming language, variables
A webpage is a text document written in HTML. This document may also contain CSS and/or JavaScript, but it’s basically an HTML text document. You could write one — including the CSS and JavaScript — using just a pencil and paper.
Despite not needing a computer to write, all three are computer languages — they are languages used by, understood by, computers (and trained humans). However only one of those (JavaScript) is a programming language.
This is a brief explanation of which is which and why.
