Squeezing A Minimalist 6502 Retrocomputer Onto A Single Breadboard

January 4, 2023 by Dan Maloney 9 Comments

Over the years, and especially lately, we’ve seen tons of single-board retrocomputer builds. That’s fine with us — the more, the merrier. But they all start to run together a bit, with little to distinguish between them. Not so this about-as-compact-as-possible 6502 computer that fits on a single breadboard.

Now, when you do the math, it seems like there’s no way that [Anders Nielsen] would have been able to fit even a minimal chipset onto a standard solderless breadboard. The 40-pin 6502 alone takes up nearly two-thirds of the connections available; add in equally large but necessary chips like the 6522 interface adapter, ROM and RAM chips, and some support ICs, and one breadboard isn’t going to cut it. Luckily, some frugal engineers at MOS back in the 70s came up with the 6507, a variant on the 6502 in a 28-pin DIP. The other key to this build is the 6532 RAM-I/O-timer chip or RIOT, which puts a tiny amount of RAM and some IO lines on a single 40-pin DIP. Along with a 28-pin ROM, a 14-pin hex inverter, and a little crystal oscillator, the entire chipset just barely fits on a single breadboard.

But what can this minimalist 6502 actually do? As you can see in the video below, anything a 555 timer can do, and maybe a little bit more. That’s not a dig, of course — [Anders] actually calls out his initial blinkenlight application as a little more than a glorified 555, and actually comes up with a marginally more complex application just to prove the point. The interesting part here is dealing with the constraints imposed by the limited resources available on this machine.

We’re looking forward to whatever comes next for this clever build. It’s hard to see how some of the plans [Anders] has for it will still fit on a single breadboard, though — these things tend to spread out as they go.

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Video: Exploring The Abandoned Birthplace Of The 6502 And Commodore 64

September 30, 2020 by Bil Herd 64 Comments

I miss my friend Dave DiOrio. He was a chip designer in the 1980’s, which made him one of the true wizards back then. We met my first day when I started at Commodore Business Machines, though my paycheck said MOS Technology on it.

MOS Technology was the birthplace of the venerable 6502 microprocessor, the VIC video chip, and the SID sound chip to name the really famous ones. It also brought us the TED Text Display chip, a whole boatload of Amiga chips, and several other chips that almost did what we wanted them to do.

I worked with magicians whose stock and trade were comprised of half-part quantum tunneling effect and half-part straight-up logic implementation. These magicians weren’t bound by the number of pins available for TTL logic, not like us lowly hardware engineers who had to string 14 and 16 pin chips together to do any real lifting.

Below the spartan offices where the designs were drawn lived the dragon otherwise known as a chip fab, short for integrated circuit fabrication plant. This beast ate sand and made wafers; slices of almost pure silicon in crystalline form with all kinds of intricate things craftily grown on top of them.

Memory Lane: Touring the Abandoned MOS Headquarters

MOS Technology was started in 1969 by Allen Bradley but only became the MOS that I think of when I talk about the good old days when Chuck Peddle and a bunch of cohorts from Motorola, including Bill Mensch, swept in and produced the 6502 microprocessor, which resembled a particular Motorola processor quite a bit, in fact a lot. Lawsuits followed.

Meanwhile the 6502 was taking over several industries as the go-to processor for everything from medical equipment to microwave ovens to home computers. It was while designing home computers that I met Dave while standing above a chip fab. I can still remember the smell of that dragon farting below our feet… its an understatement to say I miss those times.

A couple of years ago I had a chance to return to the old stomping ground as it were, and set foot (legally) inside of MOS headquarters in Norristown, PA — which had become CSG (Commodore Semiconductor Group) by the end. The basement was dirty and flooded and yet we found wafers, one from one of the computers I worked on.

The ground floor was dark and quiet, I stood at the dirty glass entrance doors looking out at a drab street and I quickly moved on before I got hit by some sort of self evident metaphor for life that would have been annoying.

The second floor was where our offices had been. The hot press of design deadlines has long since left this space, now all there is to see is the golf course out the window and a little camp fire someone had made. I got to show this video to Dave, including the view looking out his old office window, and we both smiled at the thought that it was now 35 years later.

Dave has since passed away, the world has one less wizard and as the video shows, the dragon has long since gone quiet.

A Barn Find 6502 Is Restored

February 8, 2020 by Jenny List 26 Comments

The phrase “Barn find” is normally associated with the world of older cars, where enthusiasts live in the hope that they may one day stumble upon a dusty supercar lurking unloved for decades on a remote farm. It’s not so often found in the context of electronics, but that’s the phrase that [John Culver] uses for a mid-1970s Atari arcade board that had been through a very hard time indeed and was in part coated with cow dung. It’s interesting because it sports a very early example of a MOS 6502 in a ceramic package, whose date code tells us was manufactured in week 22 of 1976.

Finding a microprocessor, even a slightly rare one, is not that great an event in itself. What makes this one interesting is the state it was in when he got it, and the steps he used to retrieve it from the board without it sustaining damage, and then to clean it up and remove accumulated rust on its pins. We are fast approaching a point at which older microprocessors become artifacts rather than mere components, and it’s likely that more than one of us with an interest in such things may one day have to acquire those skills.

We’re rewarded at the end with a picture of the classic chip passing tests with flying colours, and the interesting quirk that this is a chip with the famous rotate right bug that affected early 6502s. If you are interested in the 6502 then you should definitely read our colleague [Bil Herd]’s tribute to its recently-departed designer, [Chuck Peddle].

Hackaday Links: October 27, 2019

October 27, 2019 by Dan Maloney 13 Comments

A year ago, we wrote about the discovery of treasure trove of original documentation from the development of the MOS 6502 by Jennifer Holdt-Winograd, daughter of ~~the late~~ Terry Holdt, the original program manager on the project. Now, Ms. Winograd has created a website to celebrate the 6502 and the team that built it. There’s an excellent introductory video with a few faces you might recognize, nostalgia galore with period photographs that show the improbable styles of the time, and of course the complete collection of lab notes, memos, and even resumes of the team members. If there were a microchip hall of fame – and there is – the 6502 would be a first-round pick, and it’s great to see the history from this time so lovingly preserved.

Speaking of the 6502, did you ever wonder what the pin labeled SO was for? Sure, the data sheets all say pin 38 of the original 40-pin DIP was the “Set Overflow” pin, an active low that set the overflow bit in the Processor Status Register. But Rod Orgill, one of the original design engineers on the 6502, told a different story: that “SO” was the initials of his beloved dog Sam Orgill. The story may be apocryphal, but it’s a Good Doggo story, so we don’t care.

You may recall a story we ran not too long ago about the shortage of plutonium-238 to power the radioisotope thermoelectric generators (RTGs) for deep-space missions. The Cold War-era stockpiles of Pu-238 were running out, but Oak Ridge National Laboratory scientists and engineers came up with a way to improve production. Now there’s a video showing off the new automated process from the Periodic Videos series, hosted by the improbably coiffed Sir Martyn Poliakoff. It’s fascinating stuff, especially seeing workers separated from the plutonium by hot-cells with windows that are 4-1/2 feet (1.4 meters) thick.

Dave Murray, better known as YouTube’s “The 8-Bit Guy”, can neither confirm nor deny the degree to which he participated in the golden age of phone phreaking. But this video of his phreaking presentation at the Portland Retro Gaming Expo reveals a lot of suspiciously detailed knowledge about the topic. The talk starts at 4:15 or so and is a nice summary of blue boxes, DTMF hacks, war dialing, and all the ways we curious kids may or may not have kept our idle hands busy before the Interwebz came along.

Do you enjoy a puzzle? We sure do, and one was just laid before us by a tipster who prefers to stay anonymous, but for whom we can vouch as a solid member of the hacker community. So no malfeasance will befall you by checking out the first clue, a somewhat creepy found footage-esque video with freaky sound effects, whirling clocks, and a masked figure reading off strings of numbers in a synthesized voice. Apparently, these clues will let you into a companion website. We worked on it for a bit and have a few ideas about how to crack this code, but we don’t want to give anything away. Or more likely, mislead anyone.

And finally, if there’s a better way to celebrate the Spooky Season than to model predictions on how humanity would fare against a vampire uprising, we can’t think of one. Dominik Czernia developed the Vampire Apocalypse Calculator to help you decide when and if to panic in the face of an uprising of the ~~undead~~ metabolically ambiguous. It supports several models of vampiric transmission, taken from the canons of popular genres from literature, film, and television. The Stoker-King model makes it highly likely that vampires would replace humans in short order, while the Harris-Meyer-Kostova model of sexy, young vampires is humanity’s best bet except for having to live alongside sparkly, lovesick vampires. Sadly, the calculator is silent on the Whedon model, but you can set up your own parameters to model a world with Buffy-type slayers at your leisure. Or even model the universe of The Walking Dead to see if it’s plausible that humans are still alive 3599 days into the zombie outbreak.

Of Roach Killer And Rust Remover: Sam Zeloof’s Garage-Made Chips

November 19, 2018 by Dan Maloney 28 Comments

A normal life in hacking, if there is such a thing, seems to follow a predictable trajectory, at least in terms of the physical space it occupies. We generally start small, working on a few simple projects on the kitchen table, or if we start young enough, perhaps on a desk in our childhood bedroom. Time passes, our skills increase, and with them the need for space. Soon we’re claiming an unused room or a corner of the basement. Skills build on skills, gear accumulates, and before you know it, the garage is no longer a place for cars but a place for pushing back the darkness of our own ignorance and expanding our horizons into parts unknown.

It appears that Sam Zeloof’s annexation of the family garage occurred fairly early in life, and to a level that’s hard to comprehend. Sam seems to have caught the hacking bug early, and by the time high school rolled around, he was building out a remarkably well-equipped semiconductor fabrication lab at home. Sam has been posting his progress regularly on his own blog and on Twitter, and he dropped by the 2018 Superconference to give everyone a lesson on semiconductor physics and how he became the first hobbyist to produce an integrated circuit using lithographic processes.

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Hackaday Links: August 5, 2018

August 5, 2018 by Brian Benchoff 18 Comments

Here’s something of historical interest. The daughter of Terry Holdt, project manager for the 6502, cleaned out a garage and found shelves full of MOS Technology binders, test results, notes, instructions for processes, letters to customers, and datasheets full of errata. Some of these documents have been posted on Twitter, and efforts are underway to collect, scan, upload, and preserve them. In the distance, a man in a fabulous suit is screaming, ‘donate them to the Internet Archive’.

This is a link to Defcad, the repository of 3D printable files for weapons. Under an agreement with the US Department of State, Defcad was set to go online on August 1st. This caused much handwringing in the tech journalist thoughtspace, with reporters calling to end the first amendment because they don’t like the second. Alyssa Milano chimed in. Defcad was ordered shut down by a federal judge in the western district of Washington before going live.

As you may well be aware, Printrbot ceased operations last month. It’s sad to see them go, but they made some acceptable machines and were really pushing the boundaries of what was possible with their infinite build volume prototype printer. But what about all those existing printrbots in the wild, you might ask. Well, good news for anyone who hasn’t changed their hotend over to an E3D yet: Ubis is going to be selling hotends. Get ’em while they’re hot (or not, I don’t know how this pun works).

File this one into the ‘awesome government auctions’ category. The city of Longmont, Colorado decommissioned their tornado sirens last year because they ‘self-activated’ and malfunctioned. These sirens were put up for auction, with a winning bid of $526. Someone bought the most annoying thing imaginable for just over five bills. The world of government auctions is amazing.

Sad Without A SID? This Comes Pretty Close

July 24, 2018 by Jenny List 36 Comments

The MOS Technologies 6851, popularly known as the SID, is a legendary sound synthesiser integrated circuit from the early 1980s that is most famous for providing the Commodore 64 home computer with its ability to make noise. At the time it was significantly better than what could be found in competitor machines, making it a popular choice for today’s chiptune and demo scene artists.

There’s a snag for a modern-day SID-jockey though, the chip has been out of production for a quarter century and is thus in short supply. Emulation is a choice, but of little use for owners of original hardware so it’s fortunate that [Petros Kokotis] has produced a SID replacement using a Teensy 3.6.

The operation is simple enough, the Teensy provides all the requisite SID data lines via some level shifters for the host microcomputer, and uses [Frank Boesing]’s ReSID library to do the heavy lifting part of being a SID. You can download the code from a GitHub repository, and he’s posted a video we’ve put below the break showing a prototype in action with a real Commodore 64. The audio quality isn’t brilliant due to a phone camera recording from a very tinny speaker, but notwithstanding that it has the air of the real thing.

This isn’t the first SID we’ve seen here. How about a MIDI synth using one?

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