Ultimate Power: Lithium-Ion Batteries In Series

At some point, the 3.6 V of a single lithium ion battery just won’t do, and you’ll absolutely want to stack LiIon cells in series. When you need high power, you’ve either got to increase voltage or current, and currents above say 10 A require significantly beefed up components. This is how you’re able to charge your laptop from your USB-C powerbank, for instance.

Or maybe you just need higher voltages, and don’t feel like using a step-up converter, which brings along with it some level of inefficiency. Whatever your reasons, it’s time to put some cells into series. Continue reading “Ultimate Power: Lithium-Ion Batteries In Series”

Displays We Love Hacking: Parallel RGB

You might have seen old display panels, from 3″ to 10″, with 40-pin FFC connectors where every pin seems to be used for some data signal. We call these displays parallel RGB, or TTL RGB, or DPI, and you can find them in higher-power MCU, Raspberry Pi, and other Linux SBC projects. You deserve to know what to do with those – let’s take a look.

The idea is simple – this interface requires you to constantly send a stream of pixels to the display, and you need to send those pixels through a parallel bus. You can send up to 8 bits per color channel per pixel, which makes for 24 bits, and the 24-bit mode is indeed the standard, but in practice, many parallel RGB implementations don’t bother with more than 5-6 bits of color – two common kinds of parallel RGB links are RGB565 and RGB666. The parallel RGB interface is a very straightforward approach to sending pixels to your display, and in many cases, you can also convert parallel RGB to LVDS or VGA interfaces relatively easily!

If you’re new to it, the easiest way you can drive a parallel RGB display is from a Raspberry Pi, where the parallel RGB interface is known as DPI. This is how 800 x 480 display Pi HATs like the Pimoroni HyperPixel work – they use up almost all of the GPIOs on your Pi, but you get a reasonably high-resolution display with a low power footprint, and you don’t need any intermediate ICs either. FPGAs and some higher-grade MCUs also often have parallel RGB output capability, and surely, someone could even use the RP2040 PIO as well!

Throughout the last decade, parallel RGB has been used less and less, but you will still encounter it – maybe you’re working with an old game console like the PSP and would like to put new guts into it, maybe you’re playing with some tasty display that uses parallel RGB, or maybe you’d like to convert parallel RGB into something else while treating it with respect! Let’s go through what makes parallel RGB tick, what tools you have got to work with it, and a few tips and tricks. Continue reading “Displays We Love Hacking: Parallel RGB”

Crafting Ribbon Cables For Retro Hardware

Building a modern computer is something plenty of us have done, and with various tools available to ensure that essentially the only thing required of the end user is to select parts and have them delivered via one’s favorite (or least expensive) online retailer. Not so with retro hardware, though. While some parts can be found used on reselling sites like eBay, often the only other option is to rebuild parts from scratch. This is sometimes the best option too, as things like ribbon cables age poorly and invisible problems with them can cause knock-on effects that feel like wild goose chases when troubleshooting. Here’s how to build your own ribbon cables for your retro machines.

[Mike] is leading us on this build because he’s been working on an old tower desktop he’s calling Rosetta which he wants to be able to use to host five different floppy disk types and convert files from one type to another. Of course the old hardware and software being used won’t support five floppy disk drives at the same time so he has a few switches involved as well. To get everything buttoned up neatly in the case he’s building his own ribbon cables to save space, especially since with his custom cables he won’t have the extraneous extra connectors that these cables are famous for.

Even though, as [Mike] notes, you can’t really buy these cables directly anymore thanks to the technology’s obsolescence, you can still find the tools and parts you’d need to create them from scratch including the ribbon, connectors, and crimping tools. Even the strain relief for these wide, fragile connectors is available and possible to build into these projects. It ends up cleaning up the build quite nicely, and he won’t be chasing down any gremlins caused by decades-old degraded multi-conductor cables. And, even though [Mike] demonstrated the floppy disk drive cables in this build, ribbon cable can be used for all kinds of things including IDE drive connectors and even GPIO cables for modern electronics projects.

Continue reading “Crafting Ribbon Cables For Retro Hardware”

Building A Fake Printer To Grab Screenshots Off The Parallel Port

[Tom Verbeure] recently found himself lamenting the need to take screen grabs from an Advantest R3273 spectrum analyzer with a phone camera, as the older gear requires you to either grab tables of data over an expensive GPIB interface card, or print them to paper. Then he realized, why not make a simple printer port add-on that looks like a printer, but sends the data over USB as a serial stream?

On the hardware side, the custom PCB (KiCAD project) is based on the Raspberry Pi Pico. Obvious form factor issues aside ([Tom] did revise the PCB to make it smaller) this is a shrewd move, as this is not a critical-path gadget so using the Pico as a USB-to-thing solution is a cost-effective way to get something working with minimal risk. One interesting design point was the use of the 74LVC161284 special function bus interface that handles the 5 V tolerance that the RP2040 lacks, whilst making the project compliant with IEEE-1284 — useful for the fussier instruments.

Using the service manual of the Sharp AP-PK11 copier/printer as a reference, [Tom] again, shows how to correctly use the chip, minimizing the design effort and scope for error. The complete project, with preliminary firmware and everything needed to build this thing, can be found on the project GitHub page. [Tom] does add a warning however that this project is still being worked on so adopters might wish to bear that in mind.

If you don’t own such fancy bench instrumentation, but grabbing screenshots from devices that don’t normally support it, is more your thing, then how about a tool to grab Game Boy screenshots?

Linux Fu: Walk, Chew Gum

If you ever think about it, computers are exceedingly stupid. Even the most powerful CPU can’t do very much. However, it can do what it does very rapidly and repeatably. Computers are so fast, they can appear to do a lot of things at once, too and modern computers have multiple CPUs to further enhance their multitasking abilities. However, we often don’t write programs or shell scripts to take advantage of this. However, there’s no reason for this, as you’ll see.

Bash Support

It is surprisingly easy to get multiple processes running under Bash. For one thing, processes on either side of a pipe run together, and that’s probably the most common way shell scripts using multiprogramming. In other words, think about what happens if you write ls | more.

Under the old MSDOS system, the first program would run to completion, spooling its output to a temporary file. Then the second program will run, reading input from the same file. With Linux and most other modern operating systems, both programs will run together with the input of the second program connected to the first program’s output. Continue reading “Linux Fu: Walk, Chew Gum”

TNDLPT Brings Tandy Sound To Any DOS Computer

The Tandy 1000, among other contemporary computers and consoles of the 1980s, used the Texas Instruments SN76489 for its sound and musical output. This venerable sound chip can now be used on virtually any DOS machine, as long as it has a parallel port – thanks to the TNDLPT adapter!

The adapter consists of the SN76489, hooked up to the parallel port so that it can be addressed by the host computer via a DOS Terminate and Stay Resident program acting as a driver. With the TSR loaded, classic DOS games can be used with the TNDLPT sound output by simply selecting the Tandy 1000 soundcard at install. It can also be used in a variety of other ways, such as with the TNDY tracker for music creation, or the SBVGM soundtrack player.

For those eager to hear the soaring 3 voices (and one noise channel!) of the SN76489 once again, this is a great way to do it, with kits available on the Serdashop site for those wishing to solder up their own. Alternatively, get a different vibe with the OPL2 instead. Video after the break.

Continue reading “TNDLPT Brings Tandy Sound To Any DOS Computer”

Linux-Fu: Parallel Universe

At some point, you simply run out of processing power. Admittedly, that point keeps getting further and further away, but you can still get there. If you run out of CPU time, the answer might be to add more CPUs. However, sometimes there are other bottlenecks like memory or disk space. However, it is also likely that you have access to multiple computers. Who doesn’t have a few Raspberry Pis sitting around their network? Or maybe a server in the basement? Or even some remote servers “in the cloud.” GNU Parallel is a tool that lets you spread work across multiple tasks either locally to remote machines. In some ways, it is simple, since it looks sort of like xargs but with parallel execution. On the other hand, it has myriad options and configurations that can make it a little daunting to use. Continue reading “Linux-Fu: Parallel Universe”