A beige keyboard with blue and grey keys sits on a colorful deskmat atop a wooden desk. A small box with a round Touch ID button sits next to the keyboard.

Standalone Touch ID For Your Desktop Mac

December 26, 2022 by Navarre Bartz 1 Comment

With the proliferation of biometric access to mobile devices, entering a password on your desktop can feel so passé. [Snazzy Labs] decided to fix this problem for his Mac by liberating the Touch ID from a new Apple keyboard.

When Apple introduced its own silicon for its desktops, it also revealed desktop keyboards that included their Touch ID fingerprint reader system. Fingerprint access to your computer is handy, but not everyone is a fan of the typing experience on Apple keyboards. Wanting to avoid taping a keyboard under his desk, [Snazzy Labs] pulled the logic board from the keyboard and designed a new 3D printed enclosure for the Touch ID button and logic board so that the fingerprint reader could reside close to where the users hands actually are.

One interesting detail discovered was the significantly different logic boards between the standard and numpad-containing variants. The final enclosure designs feature both wireless and wired versions for both the standard and numpad logic boards if you should choose to build one of your own. We’re interested to see if someone can take this the next step and use the logic board to wire up a custom mechanical keyboard with Touch ID.

If [Snazzy Labs] seems familiar, you may recognize him from their Mac Mini Mini. If you’re more in the mood to take your security to the extreme, check out this Four Factor Biometric Lockbox that includes its own fingerprint reader.

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Three purple OshPark boards and a white bread board all attached using a number of jumper wires on a grey cutting mat.

An (Almost) Single-Chip Apple IIe

December 23, 2022 by Navarre Bartz 10 Comments

The Apple II is one of the most iconic microcomputers, and [James Lewis] decided to use the Mega-II “Apple IIe on a chip” from an Apple IIgs to build a tiny Apple IIe.

While there was an Apple II compatibility card using the related Gemini chip, it was initially unclear whether the Mega-II could even work outside of an Apple IIgs given the lack of documentation for either Apple II SOC. [Lewis] did finally get the Mega-II to boot after a great deal of effort in debugging and design. The system is built with three boards: the Mega-II and RAM board, a CPU board with a 65C02, and a video out board.

To simplify routing, the boards are all four layer PCBs. Unfortunately, the chips needed to make this system, especially the Mega-II, aren’t available on their own and must be harvested from an existing IIgs. [Lewis] took care to make sure any desoldering or other part removal was done in a way that it could be reversed. If you want to see all the nitty gritty details, check out his GitHub for the project.

If you want another 6502-based computer in a tiny package, why not try this one built on Perf+ boards?

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A homebrew computer built inside plexiglass cases with lots of LEDs

The Coleman Z80 Is A Modern Take On A 1970s Computer

December 20, 2022 by Robin Kearey 14 Comments

[Joshua Coleman] likes to design his own computers. Sometimes, that means drawing up bus architectures, memory maps and I/O port pinouts. Other times, he can focus his efforts more on the general aesthetics, as well as on building a great set of peripherals, as he shows in his latest ColemanZ80 project. Thanks to the RC2014 architecture defining most of the essential features of a classic Z80 computing platform, [Joshua] was able to design a modern retrocomputer that’s not only genuinely useful, but also looks as if it came off a production line yesterday.

The external design is a sight to behold: bright red laser-cut acrylic pieces form a neat, semi-transparent case with ventilation slots on the sides and lots of blinkenlights on the front. Inspired by 1970s classics like the Altair 8800, the front panel gives the user a direct view of the machine’s internal state and allows simple command inputs through a series of tumbler switches. The CPU, RAM and other basic devices are housed in one case, with all the expansion modules in a second one, linked to the mainboard through a 40-wire flatcable.

A hand-built Z80 computer's mainboard — Lots of classic chips, but also loads of hand-routed wires grace the ColemanZ80’s mainboard.

Although the mainboard closely follows the RC2014 design, [Joshua] went through a lot of effort to tune the system to his specific needs. The expansion boards he built include an NS16550 UART to replace the default 68B50, a battery-backed real-time clock, a YM2149-based sound card and even a speech synthesizer module built around the classic SP0256 chip, of Speak & Spell fame. An even more unusual feature is the presence of an AM9511, one of the earliest math coprocessors ever made, to speed up floating-point calculations. All of these modules were built entirely by hand on prototype boards: we can barely imagine how much time this must have taken.

Output devices include a VGA adapter courtesy of a Raspberry Pi Pico as well as a regular 4-digit 7-segment LED display and a set of classic HP “bubble” LEDs. [Joshua] runs several demos in his video (embedded below), ranging from computing the Mandelbrot set to playing chiptunes on the YM2149. There’s plenty of scope for further expansion, too: [Joshua] plans to build more peripherals including a floppy drive interface and a module to operate a robotic car.

This is not the first Coleman Z80 computer: the previous version ran on an architecture [Joshua] designed all by himself. We’ve seen several other impressive RC2014 derivatives, like a tiny micro version and this Altair-inspired case.

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A Straightforward Old-Fashioned DAC

December 11, 2022 by Jenny List 33 Comments

With modern microcontrollers, the process of interfacing with the analogue world is easy. Simply enable the on-board DAC or ADC, and talk to the world. If you’ve ever done this with a slightly older microprocessor, you might have encountered the DAC and ADC as chips in their own right, but how about the earliest generation of microprocessors? In those days, if an analogue component was needed, the circuit which would later be integrated on chip would have to be made from scratch. So it is that [Florian Wilhelm Dirnberger] has built a very old-style 6-bit DAC, using a circuit that would have been familiar back in the early 1970s.

At its heart are a pair of 4007 triple CMOS inverters, which form the six bits driving a resistor ladder DAC. This is simply a chair of R… 2R resistors, relying on Ohm’s law for its operation. Each successive bit contributes twice the current to the output of its predecessor, and the 4007 simply provides a buffered supply for the bits.

It’s the simplest of DACs, if not the most capable. Back in the day a typical ADC might also use this circuit, feeding a comparator alongside the input voltage. The microprocessor would count through the digital values until the comparator output bit flipped, at which point it would take the counter value as the analogue measure. You may never need to build one when your microcontroller has one built in, but it’s useful to know how simple DACs and ADCs work.

If the subject interests you, we’ve had a look at DACs including resistor ladders used in audio.

An art deco style computer made of several grey/blue boxes with silver grates on top of a maple platform.

Clean Slate Is A Vintage Amplifier-Inspired PC

December 9, 2022 by Navarre Bartz 9 Comments

Hacks that bring a vintage flair to modern electronics never get old, and [Jeffrey Stephenson] delivers with his Project Clean Slate inspired by vintage tube amps.

Thinking outside the traditional single box PC, [Jeffrey] built his computer into a series of component-specific boxes all attached to a platform housing the Micro ATX motherboard. The base is made of plywood with a birds-eye maple veneer and each of the component boxes features two different sizes of wire mesh to manipulate the viewer’s perception of the dimensions. Even the I/O and graphics card plates are custom made from aluminum for this build.

If you really want to dig into how this PC came to life, there’s a very detailed build log including every step of the process from bare board to finished product. We love when we get an inside look at the thought process behind each design decision in a build.

We’ve featured [Jeffrey] before with his Humidor Cluster, and you may also like this PC inside a vintage radio.

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An Open Source PowerPC Notebook Edges Closer

December 9, 2022 by Jenny List 21 Comments

Back in 2020, we reported on the effort to create a brand new open-source laptop platform using the PowerPC architecture. At the time they had big plans and a PCB design, and we’re very pleased to report that in the intervening two years they’ve progressed to the point of now having some real prototypes ready for testing.

Some might question why this should be necessary, after all there are plenty of laptops and more than one commonly available processor platform. But that’s to miss the point of open source hardware, that it’s as much about plurality as functionality. But if you’ve only encountered the PowerPC architecture in slightly older Macs and some game consoles, what’s the chip powering this device? The answer is, not one of those venerable chips, but the NXP T2080, a 1.8 GHz quad-core device that boasts a respectable power for a laptop.

There is of course many a hurdle still to be crossed between prototype and final device, but given the challenge of a functioning laptop it’s impressive for them to have reached this milestone at all. We look forward to seeing further iterations, and maybe, just maybe, a finished device one day. Our original coverage is here.

The 10 Kinds Of Programmers That Use Calcutron-33

December 7, 2022 by Al Williams 18 Comments

It is interesting how, if you observe long enough, things tend to be cyclical. Back in the old days, some computers didn’t use binary, they used decimal. This was especially true of made up educational computers like TUTAC or CARDIAC, but there was real decimal hardware out there, too. Then everyone decided that binary made much more sense and now it’s very hard to find a computer that doesn’t use it.

But [Erik] has written a simulator, assembler, and debugger for Calcutron-33, a “decimal RISC” CPU. Why? The idea is to provide a teaching platform to explain assembly language concepts to people who might stumble on binary numbers. Once they understand Calcutron, they can move on to more conventional CPUs with some measure of confidence.

To that end, there are several articles covering the basic architecture, the instruction set, and how to write assembly for the machine. The CPU has much in common with modern microprocessors other than the use of decimal throughout.

There have been several versions of the virtual machine with various improvements and bug fixes. We’ll be honest: we admire the work and its scope. However, if you already know about binary, this might not be your best bet. What’s more is, maybe you should understand binary before tackling assembly language programming, at least in modern times. Still, it does cover a lot of ground that applies regardless.

Made-up computers like TUTAC and CARDIAC were all the rage when computer time was too expensive to waste on mere students. There was also MIX from computer legend Donald Knuth.