Black Lives Matter - Action and Equality. ... Adafruit is open and shipping.
0

CVX4 – Parallel Port 8-Bit DAC Covox Speech Thing Clone

Check out Scali’s OpenBlog about the release of the CVX4 Covox Speech Thing clone! (Available for purchase here.)

In this video from The 8-Bit Guy he gives a breakdown of the original Covox Speech Thing (as well as the Disney Sound Source) with some good context of the era in which the device came out, and why it was so novel:

And this video breaks down what the modern clone is all about:

From Scali’s OpenBlog:

I have covered various early sound solutions from the DOS/8088 era recently, including AdLib, Sound Blaster, PCjr/Tandy’s SN76489 chip, and the trusty old PC speaker itself. One device that has yet to be mentioned however, is the Covox Speech Thing.

So it is basically an 8-bit DAC that plugs into the printer port of a PC (or in theory other computers with a compatible printer port). The DAC is of the ‘resistor ladder‘ type, which is interesting, because a resistor ladder is a passive device. It does not require a power source at all. The analog signal coming from the DAC is not very powerful though, so there is an amplifier integrated into the speakers. You can also run the output into a regular amplifier or recording equipment or such, but the output is not ‘line-level’, it is closer to ‘microphone-level’, so you may want to use a small pre-amplifier between the Covox and your other equipment.

So how does one program sound on a Covox? Well, it is very similar to outputting samples via PWM on the PC speaker, or outputting 4-bit samples by adjusting the volume register on the SN76489. That is, there is no DMA, buffering or timing inside the device whatsoever. The CPU has to write each sample at the exact time that it should be output, so you will either be using a timer interrupt running at the sampling frequency, or a cycle-counted inner loop which outputs a sample at every N CPU cycles. So this means that the sound quality is at least partly related to the replay code being used: the more accurate the timing is, the less temporal jitter the resulting analog signal will have.

So, such a simple device, with so few components (the real Covox has only one component inside, it uses a resistor ladder in a DIP package), and relying so much on the CPU, how good can this sound really? Well, my initial expectations were not that high. Somewhere in the early 90s, before I had my first sound card, I found the schematics for building your own Covox-compatible device. As said, it’s just a simple resistor ladder, so it can be built with just a few components. Various PC demos, trackers and MOD players included Covox support, and schematics. There were (and still are) also various cheap clones of the Covox available.

Read more here.


We are angry, frustrated, and in pain because of the violence and murder of Black people by the police because of racism. We are in the fight AGAINST RACISM. George Floyd was murdered, his life stolen. The Adafruit teams have specific actions we’ve done, are doing, and will do together as a company and culture. We are asking the Adafruit community to get involved and share what you are doing. The Adafruit teams will not settle for a hash tag, a Tweet, or an icon change. We will work on real change, and that requires real action and real work together. That is what we will do each day, each month, each year – we will hold ourselves accountable and publish our collective efforts, partnerships, activism, donations, openly and publicly. Our blog and social media platforms will be utilized in actionable ways. Join us and the anti-racist efforts working to end police brutality, reform the criminal justice system, and dismantle the many other forms of systemic racism at work in this country, read more @ adafruit.com/blacklivesmatter

Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.

Join 20,000+ makers on Adafruit’s Discord channels and be part of the community! http://adafru.it/discord

Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.

Join us every Wednesday night at 8pm ET for Ask an Engineer!

Follow Adafruit on Instagram for top secret new products, behinds the scenes and more https://www.instagram.com/adafruit/

CircuitPython – The easiest way to program microcontrollers – CircuitPython.org


Maker Business — To make it through a tough business cycle, layoffs should be a last resort

Wearables — Everything in its place

Electronics — The Case Of The Disappearing Capacitance

Python for Microcontrollers — Python on Microcontrollers Newsletter: New Hardware, Python Releases and Much More! #Python #Adafruit #CircuitPython @circuitpython @micropython @ThePSF

Adafruit IoT Monthly — BLE Store Capacity Indicator, Aquarium Automation, and more!

Microsoft MakeCode — Virus Destroyer!

EYE on NPI — Maxim’s Himalaya uSLIC Step-Down Power Module #EyeOnNPI @maximintegrated @digikey

New Products – Adafruit Industries – Makers, hackers, artists, designers and engineers! — NewProducts 8/6/2020 Feat. #Adafruit #ST25DV16K I2C #RFID #EEPROM #Breakout – STEMMA QT / Qwiic!

Get the only spam-free daily newsletter about wearables, running a "maker business", electronic tips and more! Subscribe at AdafruitDaily.com !



No Comments

No comments yet.

Sorry, the comment form is closed at this time.