In days gone by, a common retail hack used by some of the less honorable of our peers was the price tag switcheroo. You’d find some item that you wanted from a store but couldn’t afford, search around a bit for another item with a more reasonable price, and carefully swap the little paper price tags. As long as you didn’t get greedy or have the bad luck of getting a cashier who knew the correct prices, you could get away with it — at least up until the storekeeper wised up and switched to anti-tamper price tags.
For better or for worse, those days are over. The retail point-of-sale (POS) experience has changed dramatically since the time when cashiers punched away at giant cash registers and clerks applied labels to the top of every can of lima beans in a box with a spiffy little gun. The growth and development of POS systems is the subject of [TanRu Nomad]’s expansive video history, and even if you remember the days when a cashier kerchunked your credit card through a machine to take an impression of your card in triplicate, you’ll probably learn something.
[Taylor and Amy] love taking on retro computer projects. This week they’re building a MiniPET from Tynemouth and The Future is 8 Bit. It’s a pretty awesome kit which sadly isn’t available anymore. Taylor bought one of the last ones as part of a charity sale at the 2023 Vintage Computer Festival Southwest.
If you haven’t seen their YouTube channel yet, check it out! The two have been best friends since 1984. Their channel has just the right mix of education and comedy, with pacing fast enough to keep things interesting. It’s really refreshing to see two people enjoying a project together.
The MiniPET is of course a reproduction of the hardware in the Commodore PET, the machine which predated the VIC-20 and of course the Commodore 64. The kit starts with installing a few discrete parts — resistors, capacitors, and diodes. Then come the IC sockets. [Taylor and Amy] ran into a bit of trouble when it came time to install the chips. While installing the 40-pin 65C21 Peripheral Interface Adapter (PIA), one pin bent under the socket. [Taylor] popped the chip back out, and replaced it — which resulted in 3 bent pins!
Anyone who’s installed new DIP parts has been through this. The pins are always bent out a bit from the factory. The old “Bend it in using a table” method usually works — but if you want perfect pins, try a pin straightener. These versatile tools can even be 3D printed.
Once the pin problems are solved, it’s time to power up the kit and see if it will work. That’s when we get to see that magic moment when a project first comes to life. Check out the video – you’ll see what we mean.
At the very start of the personal computer revolution, there were relatively inexpensive boards with little more than a CPU, some memory, a display, and switches or a keypad. Some of these had expansion ports meant to allow you to build up, and some were just “trainers” to learn about computers. While you could argue that the Altair fell into this category, it had a case and a proper bus. The computers we are thinking about were usually just on a single board and — with luck — had an edge connector for expansion. Perhaps the most famous of these was the KIM-1 and [Old VCR] shows us how he brought one back to life.
These were highly popular mainly because of the low price of $245 back in 1976. For that price you got a calculator-style keyboard and LED display, 1K of RAM, and 2K of ROM. [Old VCR] has several and noticed that one was developing memory problems.
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.
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.
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].
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.
