In which we discuss GPSS: the General Purpose Simulation Language. As for as languages go, this is a unique one. It's designed for certain types of simulations. It's code is just a handy way to feed a flowchart into a computer. It's design is closer to an analog computer than it is to a programming language. Yet GPSS is Turing Complete. Step inside and prepare to be... confused!

The big source of the show:

https://dl.acm.org/doi/epdf/10.1145/960118.808382 - The Development of GPSS

Like Advent of Computing? Then check out the after show! Adjunct of Computing is now LIVE: YouTube Spotify Apple Podcasts

The Olivetti Programma 101 isn't quite like any other machine. On first glance it looks like a big desktop calculator. Inside, it's a purebred computer... but strange one. It uses twisted spring steel for memory, has no addresses, and it's machine code looks more like a spell than a program. It's existence is due, in no small part, to a man being very mean to GE engineers.

Like Advent of Computing? Then check out the after show! Adjunct of Computing is now LIVE: YouTube Spotify Apple Podcasts

I'm back to normal episodes, and I'm running out the gate with a weird one. Thoroughbred/OS was a multi-user and multi-tasking operating system for the IBM PC. It's mian interface was... BASIC of all things! What exactly is this oddity?

https://winworldpc.com/product/thoroughbred-os/662 - Try Out Thoroughbred/OS yourself

The  Standards Eastern Automatic Computer was built by the National Bureau of Standards in 1948. It started crunching numbers in 1950 and stayed in constant operation until... 1964!  This early machine, festooned with vacuum tubes, lived well past the first transistorized computers. So what exactly is SEAC doing so far into the semiconductor future?

Selected Sources:

https://archive.org/details/circularofbureau551unse/page/n7/mode/2up - Circular 551

https://sci-hub.se/10.1109/85.238389 - EDVAC Draft Report

https://sci-hub.se/10.1145/1457720.1457763 - Imaging with SEAC

In this episode I talk with Aaron Reed, author of 50 Years of Text Games. We discuss the history of computer games, interactive fiction, business "gaming", and why we all love Adventure.

You can find Aaron's work here:

http://aaronareed.net/

I recently had the chance to talk to Ben Zotto about his upcoming book: Go Computer Now! - The Story of Sphere Computers. It's all about an obscure machine powered by the Motorola 6800 that released in 1975. I figured it was the perfect faire for my audience. And... I really want to read this book!

You can back the project over at kickstarter: http://kickstarter.com/projects/bzotto/go-computer-now-the-story-of-sphere?ref=ey52pt

And find out more at Ben's sites: https://gocomputernow.com/, https://sphere.computer/

This episode I face my greatest fears: computer bugs. We are going to dive into the origin of the term, and examine the origins of debugging. The simple fact is that as soon as computers hit the scene we start finding bugs. Debugging follows very soon after. That part's not too surprising, it's the specifics that get interesting. Modern debugging methods we still use today were first developed on ENIAC, a machine that's anything but modern.

In 1981 Joe Dellinger attempted to create the perfect computer program: a virus that spread silently. In 1982 a revision of that virus broke containment. It would have remained completely hidden if it wasn't for an obscure Apple II game. Today we look at the story and motivation behind that virus, and how it slipped into the sands of time. Or... did it!? The truth is if you have an Apple II it may be infected with Dellinger's virus!

My main source: https://virus.wdfiles.com/local--files/applvir/Applvir.txt

Today we are talking about computers in space! 1964 saw the launch of Gemini I, the first spacecraft to carry an onboard computer. The aptly named Gemini Guidance Computer was responsible for guidance, navigation, and safe reentry. Built by IBM it weighed in at a tiny 59 pounds. For 1960's technology there just isn't any comparison to make, it was an amazingly small machine. What secrets does it hold? Did IBM crack some secret code to build such a tiny computer?

https://www.ibiblio.org/apollo/Gemini.html - Overview of the Gemini Guidance Computer

https://history.nasa.gov/computers/ch1-1.html - Official NASA History

https://www.ibiblio.org/apollo/Documents/GeminiProgrammingManual.pdf - How the thing was programmed

It's here! My celebratory question and answer episode! Contains ramblings on my checkered past, why computer history is important, and why FOIA is so cool.

COBOL! Just its name can strike terror in the hearts of programmers. This language is old, it follows its own strange syntax, and somehow still runs the world of finance and government. But is COBOL really as bad as it's made out to be? Today we are talking a look at the languages origins and how it's become isolated from early every other programming language in common use. Perhaps most importantly for me, we will see is Grace Hopper should really be blamed for unleashing this beast onto mainframes.

Selected Sources:

https://archive.org/details/historyofprogram0000hist - History of Programming Languages, contains Sammet's account of CODASYL

https://archive.org/details/bitsavers_codasylCOB_6843924/ - COBOL 60 Manual

https://sci-hub.do/10.1016/0066-4138%2860%2990042-2 - FLOW-MATIC/MATH-MATIC usage paper

ALOHANET was a wireless networking project started at the University of Hawaii in 1968. Initially, it had relatively little to do with ARPANET. But that relative isolation didn't last for long. As the two networks matured and connected together we start to see the first vision of a modern Internet. That alone is interesting, but what brings this story to the next level is the protocol developed for ALOHANET. Ya see, in this wireless network data delivery wasn't guaranteed. Everyone user shared a single radio channel, and terminals could talk over each other. So how did ALOHANET even function? 

Selected sources used in this episode:

https://archive.org/details/DTIC_AD0707853 - The initial 1970 ALOHANET report

https://archive.org/details/jresv86n6p591_A1b/page/n3/mode/2up - Summary paper by Kuo, contains a map of ALOHANET

https://sci-hub.do/10.1145/1499949.1499983 - Khan's 1973 PRNET paperhttps://www.eng.hawaii.edu/wp-content/uploads/2020/06/abramson1985-Development-of-the-ALOHANET.pdf - 1985 wrap-up of ALOHANET, by Abramson

Like the show? Then why not head over and support me on Patreon. Perks include early access to future episodes, and bonus content: https://www.patreon.com/adventofcomputing

This episode we take a look at the earliest days of computing, and one of the earliest forms of computer memory. Mercury delay lines, originally developed in the early 40s for use in radar, are perhaps one of the strangest technologies I've even encountered. Made primarily from liquid mercury and quartz crystals these devices store digital data as a recirculating acoustic wave. They can only be sequentially accessed. Operations are temperature dependent. And, well, the can also be dangerous to human health. So how did mercury find it's way into some of the first computers?

Like the show? Then why not head over and support me on Patreon. Perks include early access to future episodes, and bonus content: https://www.patreon.com/adventofcomputing

Where did educational games come from? According to some, the practice of using games in classrooms started in the early 60s with the appearance of the Sumerian Game. However, the story is more complicated than that. This episode we dive into the Sumerian Game, some of the earliest educational games, and the bizarre legacy of a lost piece of software.

Like the show? Then why not head over and support me on Patreon. Perks include early access to future episodes, and bonus content: https://www.patreon.com/adventofcomputing

Imagine a secret number that could be used to bring your computer to a screeching halt. In 1977 Gerry Wheeler discovered an interesting feature of Motorola's new 6800 microprocessor. There was a secret instruction that, if read, would cause the processor to stop working. He called this magic number Halt and Catch Fire, or HCF, and wrote a neat article about the operation. This was the first time the public would learn about the secret powers of HCF, but this isn't actually the beginning of the story. When it comes to HCF things are more complicated than that... but only a little bit!

The TI TMS9900 is a fascinating microprocessor. It was the first 16-bit microprocessor on the market, it has a unique architecture that makes it well suited to multitasking, and it was on IBM's shortlist to power the PC. Today we are looking at this strange chip, and the TI minicomputers that predated it's design. Along the way we will construct a theoretical TI-powered PC, and see how home computing could have changed if IBM took a slightly different path.

Like the show? Then why not head over and support me on Patreon. Perks include early access to future episodes, and bonus content: https://www.patreon.com/adventofcomputing

Project Xanadu, started in 1960, is perhaps the oldest hypertext system. It's creator, Ted Nelson, coined the term hypertext just to describe Xanadu. But it's not just a tool for linking data. Nelson's vision of hypertext is a lot more complicated than what we see in the modern world wide web. In his view, hypertext is a means to reshape the human experience. Today we are starting a dive into the strange connection between hypertext, networking, and digital utopianism.

Like the show? Then why not head over and support me on Patreon. Perks include early access to future episodes, and bonus content: https://www.patreon.com/adventofcomputing

Even after nearly 50 years C remains a force in the programming world. Anytime you brows the web, or even log into a computer, C is somewhere in the background. This episode I wrap up my series on C by looking at it's early development and spread. We will get into the 1st and 2nd C compilers ever written, and take a look at how a banned book lead to generations of avid C programmers.

Like the show? Then why not head over and support me on Patreon. Perks include early access to future episodes, and bonus content: https://www.patreon.com/adventofcomputing

C is easily one of the most influential programming languages in the world, and it's also one of the most popular languages in the world. Even after close to 50 years it remains in widespread and sustained use. In this series we are going to look at how C was developed, how it spread, and why it remains so relevant. To do that we need to start with background, and look at what exactly influenced C. This episode we are diving into some more ALGOL, CPL, BCPL, and eventually B.

Like the show? Then why not head over and support me on Patreon. Perks include early access to future episodes, and bonus content: https://www.patreon.com/adventofcomputing

One of the great things about the modern Internet is the wide range of services and content available on it. You have news, email, games, even podcasts. And in each category you have a wide range of choices. This wide diversity makes the Internet so compelling and fun to explore. But what happens when you take away that freedom of choice? What would a network look like if there was only one news site, or one place to get eamil? Look no further than THE SOURCE. Formed in 1979 and marketed as the information utility for the information age, THE SOURCE looked remarkably like the Internet in a more closed-off format. The key word here is: looked.

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The Intel 8086 may be the most important processor ever made. It's descendants are central to modern computing, while retaining an absurd level of backwards compatibility. For such an important chip it had an unexpected beginning. The 8086 was meant as a stopgap measure while Intel worked on bigger and better projects. This episode we are looking at how Intel was trying to modernize, how the 8086 fit into that larger plan, and it's pre-IBM life.

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Saga II was a program developed in 1960 that automatically wrote screenplays for TV westerns. Outwardly it looks like artificial intelligence, but that's not entirely accurate. Saga has much more in common with CNC software than AI. This episode we take a look at how the same technology that automated manufacturing found it's way into digital westerns, and how numerically controlled mills are remarkably similar to stage plays.

Clips drawn from The Thinking Machine: https://techtv.mit.edu/videos/10268-the-thinking-machine-1961---mit-centennial-film

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Sometimes an idea is so good it keeps showing up. Electronic ping-pong games are one of those ideas. The game was independently invented at least twice, in 1958 and then in 1966. But, here's the thing, PONG didn't come around until the 70s. What were theses earlier tennis games? Did Atari steel the idea for their first hit? Today we go on an analog journey to find some answers.

Like the show? Then why not head over and support me on Patreon. Perks include early access to future episodes, and bonus content: https://www.patreon.com/adventofcomputing

Lars Brinkhoff has been spearheading the effort to keep the incompatible Timesharing System alive. Today we sit down to talk about the overall ITS restoration project, software preservation, and how emulation can help save the past.

You can find the full restoration project at github: https://github.com/PDP-10/its

And follow Lars on twitter: @larsbrinkhoff

Have you ever had a computer do something you can't explain? Have you ever thought a machine had a mind of its own? In 1971 Met Life was faced with this exact conundrum. Their tape drives, for some reason, were throwing tape all over the floor every night. Systems were checked and no flaws were found, but every morning an operator would walk in on an absolute mess. What could make a healthy machine spit up it's precious tape?

Modern operating systems adhere to a pretty rigid formula. They all have users with password-protected accounts and secure files. They all have restrictions to keep programs from breaking stuff. That design has been common for a long time, but that doesn't make it the best solution. In the late 60s ITS, the Incompatible Timesharing System, was developed as a more exciting alternative. ITS was built for hackers to play, there were no passwords, any anyone who could find ITS was welcome to log in.

Like the show? Then why not head over and support me on Patreon. Perks include early access to future episodes, and bonus content: https://www.patreon.com/adventofcomputing

BASIC is a strange language. During the early days of home computing it was everywhere you looked, pretty much every microcomputer in the 70s and early 80s ran BASIC. For a time it filled a niche almost perfectly, it was a useable language that anyone could learn. That didn't happen by accident. Today we are looking at the development of BASIC, how two mathematicians started a quest to expose more students to computers, and how their creation got away from them.