An Apple ][ With A Pendulum

Clocks are a favourite project here, and we can say we’ve seen all conceivable types over the years. Just a software clock on a retrocomputer perhaps isn’t the coolest among them, but [Willem van der Jagt ]’s Apple][ clock has a little bit extra. It takes its time reference from a real pendulum, on an antique wall clock.

A proximity sensor next to a metal pendulum gives an easy way to generate a digital pulse on each pass, but leaves the question of how to transfer it to the computer. With computers of this age the circuitry is surprisingly simple, and in this case he’s sending an interrupt to the machine which the software can pick up for its timing. There is a small logic circuit between the sensor and the interrupt allowing him to gate the pendulum line, triggered from one of the output lines exposed on the Apple’s game port.

The code is written in assembly, and counts the number of pendulum swings before incrementing the number of minutes. It’s an enjoyable reminder of the days when the architecture of a computer was this accessible, and for those of us whose past lies in the Sinclair world it’s also been a little peek into something of how the Apple works.

We think this is the first pendulum-driven retrocomputer clock we’ve seen here at Hackaday, as you might understand when a clock has a pendulum it’s usually a more traditional design.

A Mysterious 6502 Apple 2 Simulator

Nice, visual simulators of CPUs such as the 6502 are usually made much later and with more modern tooling than what they simulate. But what if that wasn’t the case? What if a simulator runs on the very hardware it’s simulating?

This is what [Tea Leaves] stumbled upon when he found a mysterious disk with only “APL6502.SIM” on it. [Tea Leaves] demonstrates the simulator with a basic 6502 assembly program, revealing an animated, beautiful Apple 2 simulator that actually runs on the Apple 2! The simulator shows all the major components of a 6502 and actually animates the complete data flow of an instruction.

But why is this mysterious? It’s mysterious because – a “hello” program aside – it’s the only thing on the disk! Not so much as a single clue as to where it came from. [Tea Leaves] finds out where it comes from, including incorrectly copied disk images and a revelation at the end.

Video after the break.
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Digital Photography Comes To The Apple II

Back in the very early days of consumer digital photography, one of the first stars of the new medium came from Apple. The QuickTake 100 used a novel flat form factor and at its highest resolution could only shoot 640×480 images, but at the time it was a genuine object of desire. It came in Windows and Apple versions, and to use the Apple variant required a Mac of the day with appropriate software.

The interface was an Apple serial connector though, so it was quite reasonable for [Colin Leroy-Mira] to wonder whether it could work with Apple’s 8-bit machines. The result is QuickTake for the Apple IIc, the product that perhaps Apple should have brought us in an alternative 1994.

Fortunately the protocol has already been reverse engineered and forms part of the dcraw package, however the process of extracting the code wasn’t easy. The full resolution and colour of the original pictures has to be sacrificed, and of course once the custom serial cable has been made it’s a painfully slow process transferring the pictures. But to get anything running in this way on such elderly hardware which was never intended to  perform this task is an extremely impressive feat. We would have given anything for this, back in the 8-bit days.

If you have a QuickTake and want to use a more modern machine, we’ve got you covered there, too.

It’s A Humble ‘Scope, But It Changed Our World

A few years ago on a long flight across the North Atlantic, the perfect choice for a good read was iWoz, the autobiographical account of [Steve Wozniak]’s life. In it, he described his work replicating the wildly successful Pong video game and then that of designing the 8-bit Apple computers. A memorable passage involves his development of the Apple II’s color generation circuitry, which exploited some of the artifacts of the NTSC color system to produce a color display in a far simpler manner than might be expected. Now anyone seeking a connection with both Pong and the Apple II can have one of their very own if they have enough money because [Al Alcorn]’s Tektronix 465 oscilloscope is for sale. He’s the designer of the original Pong and used the instrument in its genesis, and then a few years later, he lent it to [Woz] for his work on the Apple II.

This may be the first time Hackaday has featured something from the catalogue of a rare book specialist, but if we’re being honest, for $135,000, it’s a little beyond the reach of a Hackaday scribe. The Tek 465 was a 100 MHz dual-trace model manufactured from 1972 to the early 1980s and, in its day, would have been a very desirable instrument indeed. This one is in pretty good condition with accompanying leads and manual and comes with a letter of authenticity and a hand-written annotation from [Al] himself on its underside. It can be seen up close in the video below the break.

As a ‘scope it’s an instrument many of us would still find useful today, but as the instrument which set in motion not one but two of the seminal moments of our craft, its historical importance can’t be overstated. We hope it will find its way into a museum or similar place where the story of those two developments can be told and that [Al] profits handsomely from its sale.

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Closeup of an Apple ][ terminal program. The background is blue and the text white. The prompt says, "how are you today?" and the ChatGPT response says, "As an AI language model, I don't have feelings, but I am functioning optimally. Thank you for asking. How may I assist you?"

Apple II – Now With ChatGPT

Hackers are finding no shortage of new things to teach old retrocomputers, and [Evan Michael] has taught his Apple II how to communicate with ChatGPT.

Written in Python, iiAI lets an Apple II access everyone’s favorite large language model (LLM) through the terminal. The program lives on a more modern computer and is accessed over a serial connection. OpenAI API credentials are stored in a file invoked by iiAI when you launch it by typing python3 The program should work on any device that supports TTY serial, but so far testing has only happened on [Michael]’s Apple IIGS.

For a really clean setup, you might try running iiAI internally on an Apple II Pi. ChatGPT has also found its way onto Commodore 64 and MS-DOS, and look here if you’d like some more info on how these AI chat bots work anyway.

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Teensy Twofer Of Plug-In Emulated Retro CPUs

[Ted Fried] wrote in with not one but two (2!) new drop-in replacements for widespread old-school CPUs: the Zilog Z80 and the Intel 8088. Both of the “chips” run in cycle-accurate mode as well as in a super turbo mode, which can run so fast that you’ll need to use the Teensy’s internal RAM just to keep up.

Both of these designs have a hardware and software component. The PCBs basically adapt the pinout of the Teensy to the target CPU, with a bunch of 74VLC latches on board to do the voltage level conversion. The rest is a matter of emulating all of the instructions on the Teensy, which is more than fast enough to keep up. If this sounds familiar to you, it’s basically the same approach that [Ted] used last year to bring us his replacement for the 6502 found in the Apple ][ and Commodore 64.

Why would you want an emulated CPU when the originals are still available? [Ted] inherited a busted Osborne I, an ancient Z80 luggable. By replacing the original Z80 with his emulation, he could diagnose the entire system, which led him to discover some bad DRAM chips and get the old beast running again. Or maybe you just want to play IBM XT games at insane speeds?

And it looks like [Ted] has updated his 6502 emulation to include the undocumented C64 opcodes, so if you’re into that scene, you should be covered as well.

If any of this tickles your fancy, head over to [Ted]’s blog, microcore labs, and follow along. Although now that he’s covered most of the famous retrocomputers, we have to ask ourselves what processor is going to be next?

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

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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