Would like to learn about logic circuits

DIYHobbyist

I have the Board of Education Rev. C with the serial BS2 and am following the What's a MicroController lab manual. After which I am interested in digital logic and would like to learn a bit about that.

Could a BS2 and BOE be connected to a series of logic components to experiment with?

I read about a program called the Parallax Logic Simulator. Is there a legal way to acquire this program for the purposes of practice before building logic circuits?

JonnyMac

Could a BS2 and BOE be connected to a series of logic components to experiment with?

Sure. BS2 is 5v TTL so it would be easy.

I read about a program called the Parallax Logic Simulator.

I didn't know Parallax had a logic simulator -- and I couldn't find a download link.

Here's a freeware program to consider:
-- https://github.com/logisim-evolution/logisim-evolution

It's pretty easy to use and you can find lots of YouTube videos that will help you get going.

A while back, Ryan Clark -- who I used to work with at Parallax -- had a Twitch stream called Transistor Tuesday where he guided viewers through going from basic gates to a very simple 4-bit computer circuit using Logisim. Sadly, those videos are no longer available, but it makes the point that Logisim is easy to use (a lot of Ryan's Twitch followers are not electronics-oriented) and can be quite useful.

DIYHobbyist

Thanks JonnyMac.

Parallax has had a Elements of Digital Logic book in the past wherein there was a Digital Trainer board and a Parallax Logic Simulator program.

I'll check out the freeware program and look for anything regarding Ryan's videos.

Also, since I got your attention. I had wired up a project in the What's a MicroController book regarding pushbuttons and LED's and the green light stayed off when I switched on the power. I hope I didn't damage any component like the BS2? Upon removing the circuit the light came on. Does the BOE have protection circuitry for these kinds of mishaps?

I had decided to build the circuit from the schematic rather than the diagram and that's where the problem started!

JonnyMac

I haven't used a BOE in years, but if memory serves, all IOs are protected with series resistors to prevent an accident connection from causing a direct short that would pop the pin. Since you're new, go very slowly, and try to keep your wiring tidy. I keep spools of 22 gauge (solid) wire handy in at least six colors so that I my breadboard wiring is easier to follow (black for ground, red for Vcc, do what you want with other colors, but be consistent).

I had decided to build the circuit from the schematic rather than the diagram and that's where the problem started!

Well, then, don't do that again until you're more accustomed to understanding schematics and how they translate to wired circuits. It's not hard, but does take a bit of practice.

Genetix

Jon,

The Homework board is the only one with protection resistors built-in.

SavageCircuits

https://forums.parallax.com/discussion/142540/diy-logic-trainer-board

I used to have one of the boards described in this thread. Not sure if the link to the software works though. See post #7 by RDL2004. This file must exist on the Parallax systems somewhere.

DIYHobbyist

Hey thanks SavageCircuits! A place to start searching. Parallax has revamped their website to the point that I think alot of the old stuff has been lost. I wonder if the waybackmachine or some other archiving website may have this content!

SavageCircuits

I haven't had much luck recovering forum posts or attachments using archive.org, however, you could email Parallax Tech Support to see if they have it in their archives.