A Blog About Random Computer Subjects
I’ve always wanted a decoder that did more than the TTL 7447 BCD to seven-segment display decoder did. I wanted the full hexadecimal output. One of my first real projects for the GAL was to create such a chip. I have an old PAL databook that was published by National Semiconductor in 1982. I pulled … Read moreGeneric Array Logic Hexadecimal Display
Let’s say you’re a programmer and your experience in digital electronics involves that one class you were required to take in college. Or…you’re a young person who is interested in learning this cool stuff, because, well… it seems cool. One option is to buy one of those learning kits and go through the tutorials. If … Read moreDigital Electronics for the Beginner
Summary In this post I’m going to talk more about creating simulation software and the difficulties of inventing something new. Writing Software is Like Working in a Sausage Factory Writing new software is more of an art than a science. Sure, we call ourselves scientists and we have methods and proven algorithms for getting things … Read moreDigital Logic Simulator Progress
Summary I’ve added the 74181 ALU TTL circuit to my logic simulator. This blog post will discuss the differences between this ALU and the 74381 that I discussed about in a previous blog post. The 74381 I added the 74381 ALU (Arithmetic Logic Unit) circuit to the logic simulator a few weeks ago and then … Read moreThe ALU
Summary I’m going to continue with my logic simulator project in this post. This project has turned into a serious obsession, ahem, hobby. My final goal is to be able to simulate a full computer circuit. TTL Logic As I’ve mentioned in my previous posts, there is a wiki page for TTL logic that lists … Read moreSimulating TTL Circuits
Introduction I’m sure readers are becoming bored with Flip Flops by now, but bear with me. The previous JK flip flop was a simple 4-NAND gate device, this circuit is the standard two flip flop device that is more stable when used in toggle mode. The Circuit The Master/Slave flip flop circuit is a bit … Read moreJK Master/Slave Flip Flop
Introduction I’ve been working on a simulation of the JK flip flop for quite some time now. I had to tweak my algorithms a bit to overcome problems with an unstable condition that I’ll discuss in this blog post. Handling Unknown Inputs One of the problems with circuits that contain feed back connections is that … Read moreJK Flip Flop Simulator
Summary In my last post I described a logic circuit simulator that I was working on. I have continued to work on this simulator source code and have discovered a difficulty in simulating a flip-flop. While researching for a creative solution to my dilemma I stumbled across a circuit called a Falstad circuit. This … Read moreFalstad Circuit Simulator and the SR Latch
Summary One of my favorite college courses was a computer simulation. This was a 400-level course that required calculus-based statistics. Our projects included a project to simulate real-world queuing problems like a Mcdonald’s drive-through line and an airport with one runway. The answers that we were required to ask were things like: How many cars … Read moreDigital Logic Simulator