Retrocomputing

1388 Articles

Lost Techniques: Bond-out CPUs And In Circuit Emulation

October 1, 2025 by 15 Comments

These days, we take it for granted that you can connect a cheap piece of hardware to a microcontroller and have an amazing debugging experience. Stop the program. Examine memory and registers. You can see and usually change anything. There are only a handful of ways this is done on modern CPUs, and they all vary only by detail. But this wasn’t always the case. Getting that kind of view to an actual running system was an expensive proposition.

Today, you typically have some serial interface, often JTAG, and enough hardware in the IC to communicate with a host computer to reveal and change internal state, set breakpoints, and the rest. But that wasn’t always easy. In the bad old days, transistors were large and die were small. You couldn’t afford to add little debugging pins to each processor you produced.

This led to some very interesting workarounds. Of course, you could always run simulators on a larger computer. But that might not work in real time, and almost certainly didn’t have all the external things you wanted to connect to, unless you also simulated them. Continue reading “Lost Techniques: Bond-out CPUs And In Circuit Emulation” →

YouTube… Over Dial Up

September 29, 2025 by 25 Comments

In the days of yore, computers would scream strange sounds as they spoke with each other over phone lines. Of course, this is dial up, the predecessor to modern internet technology, offering laughable speeds compared to modern connections. But what if dial up had more to offer? Perhaps it could even stream a YouTube video. That’s what the folks over at The Serial Port set out to find out.

The key to YouTube over dial up is a little known part of the protocol added right around the time broadband was taking off called multilink PPP. This protocol allows for multiple modems connected to a PC in parallel for faster connections. With no theoretical limit in sight, and YouTube’s lowest quality requiring a mere 175 Kbps, the goal was clear: find if there is a limit to multilink PPP and watch YouTube over dialup in the process.

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Macintosh System 7 Ported To X86 With LLM Help

September 29, 2025 by 50 Comments

You can use large language models for all sorts of things these days, from writing terrible college papers to bungling legal cases. Or, you can employ them to more interesting ends, such as porting Macintosh System 7 to the x86 architecture, like [Kelsi Davis] did.

When Apple created the Macintosh lineup in the 1980s, it based the computer around Motorola’s 68K CPU architecture. These 16-bit/32-bit CPUs were plenty capable for the time, but the platform ultimately didn’t have the same expansive future as Intel’s illustrious x86 architecture that underpinned rival IBM-compatible machines.

[Kelsi Davis] decided to port the Macintosh System 7 OS to run on native x86 hardware, which would be challenging enough with full access to the source code. However, she instead performed this task by analyzing and reverse engineering the System 7 binaries with the aid of Ghidra and a large language model. Soon enough, she had the classic System 7 desktop running on QEMU with a fully-functional Finder and the GUI working as expected. [Kelsi] credits the LLM with helping her achieve this feat in just three days, versus what she would expect to be a multi-year effort if working unassisted.

Files are on GitHub for the curious. We love a good port around these parts; we particularly enjoyed these efforts to recreate Portal on the N64. If you’re doing your own advanced tinkering with Macintosh software from yesteryear, don’t hesitate to let us know.

Decorate Your Neck With The First Z80 Badge

September 28, 2025 by 4 Comments

Over the years, we’ve brought you many stories of the creative artwork behind electronic event badges, but today we may have a first for you. [Spencer] thinks nobody before him has made a badge powered by a Z80, and we believe he may be right. He’s the originator of the RC2014 Z80-based retrocomputer, and the badge in question comes from the recent RC2014 Assembly.

Fulfilling the function of something you can write your name on is a PCB shaped like an RC2014 module, with LEDs on all the signal lines. It could almost function as a crude logic analyser for the system, were the clock speed not far too high to see anything. To fix this, [Spencer]’s badge packs a single-board RC2014 Micro with a specially slow clock, and Z80 code to step through all memory addresses, resulting in a fine set of blinkenlights.

Thus was created the first Z80-based event badge, and we’re wondering whether or not it will be the last. If you’re curious what this RC2014 thing is about, we reviewed the RC2014 Micro when it came out.

A Walk Down PC Video Card Memory Lane

September 28, 2025 by 30 Comments

These days, video cards are virtually supercomputers. When they aren’t driving your screen, they are decoding video, crunching physics models, or processing large-language model algorithms. But it wasn’t always like that. The old video cards were downright simple. Once PCs gained more sophisticated buses, video cards got a little better. But hardware acceleration on an old-fashioned VGA card would be unworthy of the cheapest burner phone at the big box store. Not to mention, the card is probably twice the size of the phone. [Bits and Bolts] has a look at several old cards, including a PCI version of the Tseng ET4000, state-of-the-art of the late 1990s.

You might think that’s a misprint. Most of the older Tseng boards were ISA, but apparently, there were some with the PCI bus or the older VESA local bus. Acceleration here typically meant dedicated hardware for handling BitBlt and, perhaps, a hardware cursor.

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NEC V20: The Original PC Processor Upgrade

September 27, 2025 by 15 Comments

In the early 1980s, there was the IBM PC, with its 4.77 MHz Intel 8088 processor. It was an unexpected hit for the company, and within a few years there were a host of competitors. Every self-respecting technology corporation wanted a piece of the action including processor manufacturers, and among those was NEC with their V20 chip and its V30 sibling. From the outside they were faster pin-compatible 8088 and 8086 clones, but internally they could also run both 8080 and 80186 code. [The Silicon Underground] has a look back at the V20, with some technical details, history, and its place as a PC upgrade.

For such a capable part it’s always been a surprise here that it didn’t take the world by storm, and the article sheds some light on this in the form of an Intel lawsuit that denied it a critical early market access. By the time it was available in quantity the PC world had moved on from the 8088, so we saw it in relatively few machines. It was a popular upgrade for those in the know back in the day though as it remains in 2025, and aside from its immediate speed boost there are a few tricks it lends to a classic PC clone. The version of DOS that underpinned Windows 95 won’t run on an 8086 or 8088 because it contains 8016 instructions, but a V20 can run it resulting in a much faster DOS experience. One to remember, if an early PC or clone cones your way.

Hungry for the good old days of DOS? You don’t need to find 80s hardware for that.

First Transistor Computer Reborn

September 21, 2025 by 15 Comments

Ok, we’ll admit it. If you asked us what the first transistorized computer was, we would have guessed it was the TC from the University of Manchester. After all, Dr. Wilkes and company were at the forefront and had built Baby and EDSAC, which, of course, didn’t use transistors. To be clear, we would have been guessing, but what we didn’t know at all was that the TC, with its magnetic drums and transistors in 1955, had a second life as a commercial product from Metropolitan-Vickers, called the Metrovick 950. [Nina Kalinina] has a simulator inspired by the old machine.

The code is in Python, and you can find several programs to run on the faux machine, including the venerable lunar lander. If you haven’t heard of the Metrovick, don’t feel bad. Oral histories say that only six or seven were ever built, and they were used internally within the company.

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