A 6502 Computer, With Acres Of Breadboard And Dozens Of Chips

Imagine you’re time-warped back to 1979 and tasked with constructing a personal computer. Could you do it? [RadicalBrad] thinks he can, and his 6502-based “Super VIC” build looks like it’s off to a great retrocomputing start.

Most emulations of old hardware these days go the FPGA route, and while we respect those projects immensely, there’s something to be said for applying a highly artificial constraint at the outset of a project. [RadicalBrad] chose to design like it’s 1979, and limited his ode to the machines of his youth to the 6502 CPU and logic and RAM chips available before 1980. The computer will support NTSC video output and 4-channels of 8-bit sound. No circuit boards will be used – everything is to be assembled on solderless breadboards. So far he has 48 (!) of them ganged together, which sounds like an enormous amount of space to work with, but he still found things crowded enough that some of the DIP bodies were trimmed a bit to fit more closely on the breadboards. The SRAM posed a problem, though, in that the 512K chips he wanted were not available in DIPs. To stay faithful to the constraints, he soldered the SOJ-packaged RAM chips into 40-PIN DIP headers – all 25 chips! We can’t recall a PC of the era sporting 12 megabytes of RAM, but no matter – it’s too cool not to love.

[RadicalBrad] has his work cut out for him, and this could take years to finish. We’re keen to follow his progress and can’t wait till it boots for the first time. Until it does, we’ll just gaze upon such discrete computing wonders as this almost-as-simple-as-possible computer, or even this delightfully noisy adder for a relay computer.

The Dual In-Line Package and How It Got That Way

For most of human history, our inventions and innovations have been at a scale that’s literally easy to grasp. From the largest cathedral to the finest pocket watch, everything that went into our constructions has been something we could see with our own eyes and manipulate with our hands. But in the middle of the 20th century, we started making really, really small stuff: semiconductors. For the first time, we were able to create mechanisms too small to be seen with the naked eye, and too fine to handle with our comparatively huge hands. We needed a way to scale these devices up somewhat to make them useful parts. In short, they needed to be packaged.

We know that the first commercially important integrated circuits were packaged in the now-familiar dual in-line package (DIP), the little black plastic millipedes that would crawl across circuit boards for the next 50 years. As useful and versatile as the DIP was, and for as successful as the package became, its design was anything but obvious. Let’s take a look at the dual in-line package and how it got that way.

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Minimal Blinky Project Makes The Chip The Circuit Board

We’ve got a thing for projects that have no real practical value but instead seek to answer a simple yet fundamental question: I wonder if I can do that? This dead-bug style 555 blinky light is one of those projects, undertaken just to see how small a circuit can be. Pretty small, as it turns out, and we bet it can get even smaller.

[Danko]’s minimal circuit is about as small as possible for the DIP version of the venerable 555 chip. The BOM is stripped to the bone: just the chip, three resistors, a capacitor, and an LED. All the discrete components are SMDs in 0805. The chip’s leads are bent around the package to form connections, and the SMDs bridge those “traces” to complete the circuit. [Danko] shows the build in step-by-step detail in the video below. There’s some fairly fine work here, but we can’t help wondering just how far down the scale this could be pushed. We know someone’s made a smaller blinky using a tiny microcontroller, but we’d love to see this tried with the BGA version of the chip which is only 1.4 mm on a side.

Cheers to [Danko] for trying this out and having some fun with an old chip. He seems to have a bit of a thing for the 555; check out this cute robot sculpture that’s built around the chip.

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Marvel at Soviet-era Smart Display’s Tiny Size

The Soviet-era 490IP1 LED. The digit is a mere 2.5 mm in height. Pictured with the Texas Instruments TIL306. [image: industrialalchemy.org]
It’s easy to assume that older components will be less integrated and bulkier than we might otherwise expect. Then something seems ahead of its time, like the teeny-tiny 490IP1 LED which was produced in the former Soviet Union. [AnubisTTP] obtained and shared images of this tiny integrated single digit LED display in which the number measures a scant 2.5 mm tall; in production it was made easier to read with an external bubble lens magnifier clipped to the outside. The red brick the 490IP1 is pictured with is the Texas Instruments TIL306, a relatively normal sized DIP component with similar functionality.

The 490IP1 is called an intelligent LED display because the package contains a decade counter and driver circuitry for the integrated seven-segment LED digit, complete with a carry signal that meant multiple displays could be chained together. It is notable not just due to its size, but because the glass cover makes it easy to see the die inside, as well as the wire-bonded pads.

It’s always fascinating to see glimpses of the development path that display technologies took. It’s easy to take a lot of it for granted today, but back before technology was where it is now, all sorts of things were tried. Examples we’ve seen in the past include the fantastic (and enormous) Eidophor projector which worked by drawing images onto a rotating disk of oil with an electron gun. On the smaller end of things, the Sphericular display used optics and image masks to wring a compact 0-9 numerical display out of only a few lamps at the back of a box.

3D Printed Tool Tips to Straighten DIP Chips and Unstraighten Resistors

Watching someone assemble a kit is a great way to see some tools you may have not encountered before and maybe learn some new tricks. During [Marco Reps’] recent build of a GPS synchronized Nixie clock kit we spied a couple of handy tools that you can 3D print for your own bench.

Fresh from the factory Dual Inline Package (DIP) chips come with their legs splayed every so slightly apart — enough to not fit into the carefully designed footprints on a circuit board. You may be used to imprecisely bending them by hand on the surface of the bench. [Marco] is more refined and shows off a neat little spring loaded tool that just takes a couple of squeezes to neatly bend both sides of the DIP, leaving every leg the perfect angle. Shown here is a 3D printed version called the IC Pin Straightener that you can throw together with springs and common fasteners.

Another tool which caught our eye is the one he uses for bending the metal film resistor leads: the “Biegelehre” or lead bending tool. You can see that [Marco’s] tool has an angled trench to account for different resistor body widths, with stepped edges for standard PCB footprint spacing. We bet you frequently use the same resistor bodies so 3D printing is made easier by using a single tool for each width. If you really must copy what [Marco] is using, we did find this other model that more closely resembles his.

As for new tricks, there are a lot of small details worth appreciating in the kit assembly. [Marco] cleans up the boards using snips to cut away the support material and runs them over sandpaper on a flat surface. Not all Nixie tubes are perfectly uniform so there’s some manual adjustment there. And in general his soldering practices are among the best we’ve seen. As usual, there’s plenty of [Marco’s] unique brand of humor to enjoy along the way.

We have a warm spot in our heart for simple tools you can whip up on the ‘ole 3D printer. Check out the PCB vise, a set of ball and socket helping hands, and a collection of toolbag essentials.

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RIP DIP ARM

Every month, semiconductor manufacturers across the globe retire old devices. A product that has been superseded, isn’t selling well, or maybe whose application has declined, is removed from the catalogue and ceases to be manufactured. Usually these moments pass unnoticed, just one old device among many. Who is going to remark upon the demise of a chip for a VGA card for example, or a long-ago-left-behind Flash memory chip?

One has come to our attention that is pretty unremarkable, but that could concern some of our readers. NXP have stopped manufacturing the LPC810M021FN8. What on earth is an LPC810M021FN8, you ask, the answer being that it appears to have been the last microcontroller with an ARM core available in a DIP package. Even that in itself is hardly earth-shattering, for if you really must use an ARM core rather than any of the myriad 8, 16, or 32 bit microcontrollers still available you can always get a DIP breakout board for a small surface mount chip.

This turn of events comes as a reminder that, while breadboard-friendly and popular among a section of our community, DIP packages are now particularly old-school. Other once-popular devices such as the LPC1114 have also long-since ceased to be available in this format, and we have to wonder how long we will be able to take advantage of DIP packages for some of the other microcontroller families.

A few years ago this news might have come as something of a disaster, but it now has more of a sense of the passing of a bygone era. It’s normal to use microcontroller dev boards in a larger DIP format for prototyping, so maybe getting used to a bit of surface-mount soldering on a break-out board will be only for the truly hard-core when the last DIP package has been retired. Other than that of course, the 555 is still available in a DIP8, and you can make anything with one of them!

If you didn’t have a chance to take the 810 for a test drive, the usual suppliers still list it in stock, Adafruit have a starter pack for it, and it will no doubt be possible to find it in small quantities for years to come.

[Thanks Tod E. Kurt for the tip]

Dead-Bug Logic Probe in a Magic Marker

Logic probes are simple but handy tools that can be had for a couple of bucks. They may not be the sexiest pieces of test gear, nor the most versatile, but they have their place, and building your own logic probe is a great way to understand the tool’s strength and weaknesses.

[Jxnblk]’s take on the logic probe is based on a circuit by [Tony van Roon]. The design hearkens back to a simpler time and is based on components that would have been easy to pick up at any Radio Shack once upon a time. The logic section is centered on the venerable 7400 quad 2-input NAND gate in the classic 14-pin DIP format. The gates light separate LEDs for high and low logic levels, and a 555 timer chip in a one-shot configuration acts as a pulse stretcher to catch transients. The DIP packages lend themselves to quick and dirty “dead bug” construction, and the whole thing fits nicely into a discarded marking pen.

dead-bug-logic-probe-in-marker-body

It’s a simple build and a nice form factor for a useful tool, but for an even slimmer package like an old syringe you’ll probably have to go with SMD components. And when you graduate from the simple logic probe, you might want to check out the capabilities of this smart probe.