Using The Pi Pico As ‘Programmable Hardware’ For The Apple II

When we think of programmable hardware, we think of FPGAs. But they’re not the only option. [Oliver Schmidt] has been exploring how the Raspberry Pi Pico can serve in such a role for the classic Apple II. The talk was presented at the KansasFest event this year, and it’s well worth diving into!

[Oliver] has developed A2Pico. It’s a series of Apple II peripheral cards that are based around the Raspberry Pi Pico, as you might have guessed. [Oliver] has been working in the area since 2021 with one [Glenn Jones], with the duo experimenting with connecting the versatile microcontroller directly to the slot bus of the Apple II. [Ralle Palaveev] then chimed in, developing the A2Pico hardware with solely through-hole components for ease of assembly.

A number of cards have been developed based on A2Pico, including a storage device, a Z80 CP/M card, and a specialized card to play Bad Apple on the IIGS. It’s all thanks to the versatility of the programmable I/O (PIO) peripheral inside the Raspberry Pi Pico. This device enables the Pico to be reprogrammed to handle all sorts of complicated tasks at great speed. This is particularly useful when using it to bit-bang a protocol or talk with another machine, and it serves perfectly well in this role. Basically, by reprogramming the Pico and its PIO, the A2Pico design can become any one of a number of different add-on cards.

It’s well worth diving into this stuff if you’ve ever contemplated building your own peripheral cards for 8-bit and 16-bit machines. We’ve seen some other great add-on cards for vintage machines before, too.

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Nice Retro Displays Set This Watch On Edge

A common design language for watches has evolved ever since they first started popping up in the 1500s. Whether worn on the wrist or in a pocket, watches are relatively slim front to back, with the display mounted on the face. That’s understandable given the imperatives of human anatomy. Still, it’s not the only way to arrange things, as this very cool LED matrix watch with an edge-mounted display demonstrates.

True, the unique form factor of this watch wasn’t really the point of the whole project. Rather, [Vitali]’s design was driven by a couple of things. First off were the extremely cool Hewlett Packard HDSP-2000 displays, with four 5×5 5×7 LED matrices shining through the clear cover of a DIP-12 package. Also visible through the cover are the shift registers that drive the matrices, complete with gold bonding wires.

The main attraction for [Vitali], though, was the challenge of working within the limits of the ATtiny85 he chose to run the watch. The MCU’s limited IO made hardware multiplexing necessary, no mean feat given the limited resources and real estate available. He still managed to pack everything in, with the unique edge-mount display coming from the LEDs bridging the space between the two main PCBs. Everything fits into a nice wood veneer case, although we think it looks just fine without it. [Vitali] puts it through its paces in the short video below.

Hats off to [Vitali] for a great-looking project that pushed his limits. We just love these displays, too; of course, it’s not the first time we’ve seen them put to similar use.

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