Advent of Computing

Welcome to Advent of Computing, the show that talks about the shocking, intriguing, and all too often relevant history of computing. A lot of little things we take for granted today have rich stories behind their creation, in each episode we will learn how older tech has lead to our modern world.

Episode 170 - Thoroughbred/OS 11/10/2025

Episode 170 - Thoroughbred/OS 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? - Try Out Thoroughbred/OS yourself /episode/index/show/adventofcomputing/id/38969835

Episode 169.5 - Ben Zotto and the Story of Sphere Computers 11/01/2025

Episode 169.5 - Ben Zotto and the Story of Sphere Computers 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: And find out more at Ben's sites: /episode/index/show/adventofcomputing/id/38873890

Episode 169 - Dellinger's Viruses 10/26/2025

Episode 169 - Dellinger's Viruses 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: /episode/index/show/adventofcomputing/id/38784345

Episode 168 - Halt and Catch Fire 10/19/2025

Episode 168 - Halt and Catch Fire 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! /episode/index/show/adventofcomputing/id/38623100

Episode 167 - The Tape That Unwound Itself 10/12/2025

Episode 167 - The Tape That Unwound Itself 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? /episode/index/show/adventofcomputing/id/38554770

Episode 166 - Beyond the PDP-11 10/05/2025

Episode 166 - Beyond the PDP-11 My trilogy on the PDP-11 concludes with a look at the far flung places this computer can take us. In this episode we look at some issues with claims of the PDP-11's linage, smuggling, Hungarian-made microcode, and much more. Along the way we answer the question: if the PDP-11 was such a good design then where was it during the home computing boom of the 80s? /episode/index/show/adventofcomputing/id/38472225

Episode 165 - LSI-11 09/21/2025

Episode 165 - LSI-11 This episode we continue my series on the PDP-11 by examining how DEC adapted to the advent of the microprocessor. Along the way we will see how the PDP-11 inspired new generations of computers, and the surprising connection to early digital hobbyists. /episode/index/show/adventofcomputing/id/38293500

Episode 164 - LGP-30 LIVE! from VCF West 09/07/2025

Episode 164 - LGP-30 LIVE! from VCF West Last weekend I had the chance to talk about the LGP-30 and my emulation project at VCF West in Mountain View, CA. The showrunners will be posting a full video later, but that takes a while to go live. In the meantime, here's the audio I siphoned off the sound board and my slide deck. View my slides here: View the emulator at: /episode/index/show/adventofcomputing/id/38114010

Episode 163 - Ever Heard of the PDP-11? 08/24/2025

Episode 163 - Ever Heard of the PDP-11? The DEC PDP-11 is one of the most influential minicomputers of all time. Some would even call it the most influential computer of all time. But where exactly did it come from? How was it designed? This episode is the start of a 3 part series that will look at how the PDP-11 was created, adapted to changes, and the strange places it ended up. /episode/index/show/adventofcomputing/id/37932410

Episode 162 - CSIRAC, Australia's First Computer 08/10/2025

Episode 162 - CSIRAC, Australia's First Computer In 1949 CSIRAC sprung to life in a lab in Sydney, Australia. It was a very early stored program computer. All machines of the era were unique. But CSIRAC, well, it was very unique indeed. Selected Sources: - The Music of CSIRAC - Pearcy and Beard on CSIRAC /episode/index/show/adventofcomputing/id/37749775

Episode 161 - The IAS Machine 07/13/2025

Episode 161 - The IAS Machine The first batch of digital computers emerge directly following WWII. The hallmark of this generation is uniqueness: no two computers are the same. However, there is a machine that bucks that trend. The IAS Machine, built in Princeton in the late 1940s, served as the inspiration for at least a dozen later computers. But how similar were these Princeton-class computers? What exactly was so special about the IAS Machine? And how does good 'ol Johnny von Neumann get tied up in all of this? Selected Sources: Bigelow Oral History - Prelin IAS Machine Report - https://www.ias.edu/sites/default/files/library/Prelim_Disc_Logical_Design.pdf /episode/index/show/adventofcomputing/id/37386160

Episode 160 - What can Lunar Lander tell us about FOCAL? 06/29/2025

Episode 160 - What can Lunar Lander tell us about FOCAL? Lunar Lander is one of the best loves video games of all time. The game was created in 1969 as an homage to the recent Apollo 11. From there it would only spread. Just about anything that can print text has it's own version of Lunar Lander. The early history of this game is mixed up with something weird: two nearly identical programming languages. Today we will be using the history of Lunar Lander as a good excuse to look at an obscure tongue called FOCAL. This language is so close to BASIC that direct line-by-line translation is possible. But are the two connected? /episode/index/show/adventofcomputing/id/37208450

Episode 159 - The Intel 286: A Legacy Trap 06/15/2025

Episode 159 - The Intel 286: A Legacy Trap In 1982 Intel released the iAPX 286. It's was the first heir to the smash-hit 8086. But the 286 was developed before the IBM PC put an Intel chip on every desk. It's design isn't influence by the PC. Rather, it reaches further into the past. Today we are looking at the strange melding of old technology, new ideas, and compatibility that lead to the 286. /episode/index/show/adventofcomputing/id/37011985

Episode 158 - INTERCAL RIDES AGAIN - Restoring a Lost Compiler 06/01/2025

Episode 158 - INTERCAL RIDES AGAIN - Restoring a Lost Compiler In 1973 the world caught it's first glimpse of INTERCAL. It's a wild and wacky language, somewhere between comedy and cutting satire. But the compiler was never circulated. There would be later implementations, but that original compiler remained lost to time. That is, until now. This episode covers how the original source code was found, and my attempt to get it up and running. Get the source code for INTERCAL72 here: Read the original INTERCAL manual: /episode/index/show/adventofcomputing/id/36801360

Episode 157 - Only S1 Users Will Survive! 05/11/2025

Episode 157 - Only S1 Users Will Survive! The S1 operating system can do it all! It can run on any computer, read any disk, and execute any software. It can be UNIX compatible, DOS compatible, and so, so much more! But... can S1 ship? Today we are talking about an operating system that sounds too good to be true. Is it another example of vaporware? Or is S1 really the world's most sophisticated operating system? /episode/index/show/adventofcomputing/id/36520305

Episode 156 - RPG, a Different Paradigm? 04/27/2025

Episode 156 - RPG, a Different Paradigm? How do you make a computer act less like a computer? It sounds like some kind of riddle, but in the early 1960s it was an actual problem. As IBM customers transitioned from tabulators to computers they ran into all sorts of practical issues. Programmers became a hot commodity. But how do you find a programmer in 1959? And how can you even afford such a luxury? Wouldn't it be better if you could just use your new computer as a tabulator? Well, with RPG, all that and more was possible. /episode/index/show/adventofcomputing/id/36324065

Episode 155 - LINC 04/13/2025

Episode 155 - LINC In the early 1960s a neat little machine came out of MIT. Well, kind of MIT. The machine was called LINC. It was small, flexible, and designed to live in laboratories. Some have called it the first personal computer. But, is that true? Does it have some secret that will unseat my beloved LGP-30? And how does DEC fit into the picture? /episode/index/show/adventofcomputing/id/36111545

Episode 154 - ACTing Up 03/30/2025

Episode 154 - ACTing Up The LGP-30 is one of my favorite computers. It's small, scrappy, strange, and wonderous. Among its many wonders are two obscure languages: ACT-I and ACT-III. In this episode we are exploring the ACTS, how the LGP-30 was programmed in practice, and why I've been losing sleep for the last few weeks. /episode/index/show/adventofcomputing/id/35919240

Episode 153 - The Keypact Mystery 03/17/2025

Episode 153 - The Keypact Mystery When I was down at VCF SoCal I ran into a strange machine: the Keypact Micro-VIP. It's a terminal without a keyboard, covered in dials, with a speaker and a switch labeled "voice". This chance encounter with the unknown sent me down a wild path. It involved the creeping spread of computing, chicken feed, door to door life insurance salesmen, and at least one early hacker. /episode/index/show/adventofcomputing/id/35717720

Episode 152 - LIVE at VCF - Reviving Retro Panel 03/02/2025

Episode 152 - LIVE at VCF - Reviving Retro Panel A special treat from VCF SoCal. While visiting I had the chance to host a panel on restoration and preservation. I was joined by: David from Usagi Electric ( Rob from Souther Amis ( Jim, Former Executive Director Computer Museum of America ( /episode/index/show/adventofcomputing/id/35494340

Episode 151 - The Friden Flexowriter 02/03/2025

Episode 151 - The Friden Flexowriter Have you ever looked at an old computer and seen a weird typewriter thing tacked on? In most cases that's a device called a Flexowriter. It's half electric typewriter, half teleprinter, half tape reader, and all business! This episode we are chronicling the rise, fall, and weird business dealings of the Flexowriter. /episode/index/show/adventofcomputing/id/35110580

Episode 150 - Starting Windows Up 01/20/2025

Episode 150 - Starting Windows Up In the modern day Windows is a power house, but that wasn't always the case. In this episode we are looking at the fraught development of Windows 1.0. During development it was called vaporware, it was panned in the press, roasted at at least one trade show, and even called... "eclectic". Through it all a vision in lime green would take form. /episode/index/show/adventofcomputing/id/34902820

Episode 149 - IDRIS Is Not UNIX 01/05/2025

Episode 149 - IDRIS Is Not UNIX This episode we are taking a trip back to UNIX world. We're looking at IDRIS, the first clone of UNIX. It was supposed to be highly compatible, but use no code from Bell Labs. IDRIS ran on everything from the Intel 8080 up to the IBM System/370. There was even a version that could run MS-DOS programs. Sound too good to be true? Well, that may be the case. Selected Sources: - A Quarter Century of UNIX - Co-Idris disk images and executables /episode/index/show/adventofcomputing/id/34722110

Episode 148 - Is BLISS Ignorance? 12/22/2024

Episode 148 - Is BLISS Ignorance? In 1970 a little language called BLISS emerged from Carnegie Mellon University. It was a systems language, meant for operating systems and compilers. It was designed, in part, as a response to Dijkstra's famous Go To Considered Harmful paper. It had no data types. It used the most bizzare form of the pointer I've ever seen. And it was a direct competitor to C. Sound interesting, yet? Selected Sources: - Readings on BLISS - A History of BLISS /episode/index/show/adventofcomputing/id/34566285

Episode 147 - Molecular Electronic Computer 12/09/2024

Episode 147 - Molecular Electronic Computer In 1961 Texas Instruments unveiled the Molecular Electronic Computer, aka: Mol-E-Com. It was a machine that fit in the palm of your hand, but had all the power of a much larger computer. This was in an age of hefty machines, which made the achievement all the more marvelous. How was this even possible? It was all thanks to the wonders of molecular electronics, and a boat load of funding from the US Air Force. Selected Sources: - Invention of the Integrated Circuit, Kilby - Investigation of Silicon Functional Blocks, TI - Silicon Semiconductor Networks, TI /episode/index/show/adventofcomputing/id/34329570

Episode 146 - The Z4 11/25/2024

Episode 146 - The Z4 The Z4, completed by Konrad Zuse in 1945, is a computer with a wild story. It was made from scrounged parts, survived years of bombing raids, moved all around Berlin, and eventually took refuge in basements and stables. In this episode we will follow the Z4's early days, and look at how it fits into the larger picture of Zuse's work. Along the way there is looting, rumors, and even... IBM! Selected Sources: The Computer, My Life - Konrad Zuse's autobiography - Plankalkul, F.L. Bauer and H. Wossner - Architecture of the Z4, Rojas /episode/index/show/adventofcomputing/id/34125921

Episode 145 - Zuse's Mysterious Machines 11/11/2024

Episode 145 - Zuse's Mysterious Machines In 1933 Konrad Zuse, a German civil engineer, caught the computing bug. It would consume the rest of his life. According Zuse he invented the world's first digital computer during WWII, working in near total isolation within the Third Reich. How true is this claim? Today we are looking at Zuse's early machines, the Z1, Z2, and Z3. Selected Sources: The Computer -- My Life, by Konrad Zuse - Z1 Architecture paper by Rojas - Z3... Turing Complete? also by Rojas /episode/index/show/adventofcomputing/id/33869502

Episode 144 - RABBITS 10/27/2024

Episode 144 - RABBITS :(){ :|:& };: /episode/index/show/adventofcomputing/id/33624697

Episode 143 - The Haunted Hard Drive 10/20/2024

Episode 143 - The Haunted Hard Drive Have you ever felt like a computer just refuses to work? Like a machine has a mind of it's own? In 1970 a hard drive at the National Farmers Union Corp. office decided to do just that. That year it started crashing for apparently no reason. It would take 2 years and 56 crashes to sort out the problem. The ultimate solution would leave more questions than answers. Was the hard drive haunted? Or was something else at play? Selected Sources: - Computer Crime - Computer World article /episode/index/show/adventofcomputing/id/33341512

Episode 142 - OS and JEDGAR 10/13/2024

Episode 142 - OS and JEDGAR This time we are diving back into the Jargon File to take a look at some hacker folklore. Back in the day hackers at MIT spent their time spying on one another's terminals. That is, until some intrepid programmer found a way to fight back. Selected Sources: - OS and JEDGAR - ITS restoration project /episode/index/show/adventofcomputing/id/33340372

Advent of Computing

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