history – Observations from Uppsala

New Job, New Simulator

As already leaked by LinkedIn, I recently started a new job at ASTC, as Global Technical Marketing Manager for the VLAB virtual platform product. This is my first major change of job I since I joined Virtutech to work on the Simics simulator back in 2002. It is both a big change and a small change – staying in the world of virtual platforms, but working with a new product that is quite different from Simics. In fact, more things are different and new and fresh than the same…

Reversing out of Reverse

The Intel Simics simulator version 7 removed a long-standing feature from the simulator framework. Reverse execution is no longer available. In its place, in-memory snapshots were introduced, which arguably offer most of the benefits at a lower implementation cost. What happened? I’ve been asked about the reasoning behind the chance on several occasions since I left Intel. I’d like to share my perspective on the decision, as it highlights the challenges of turning an idea into a robust, shippable feature.

“Processor Performance Insights and Optimization” – Computer and System Architecture Unraveled Event Four

Finally, the fourth CaSA, Computer and System Architecture Unraveled, meetup happened on November 6. It took far too long to get it organized, but we finally did it. The theme was about processor performance analysis and efficient processor implementation, offering two talks from very different perspectives. The location was almost the same as before, on the 19^th floor of the Kista Science Tower building. Once more thanks to the sponsorship from Vasakronan and Kista Science City.

Vilnius – History, Russia, Ukraine

We spent a few days in Vilnius at the end of October. Rather late in the tourist season, but the city was still open for business. It was a very good experience. Vilnius is one of the friendliest and cleanest places I have visited. Definitely on the “recommended” list. Here are some assorted notes from what we saw.

Useful Instruction Set Computing

I tend to get into discussions about computer processor instruction-set architecture (ISA) design. ISA design is far from my day job, but it is an interesting topic where everyone working with computers at the machine level have opinions. Typically based on a mix of personal experience and fond memories of particular machines. This in turn leads to intricate and intriguing arguments. In this blog, I will talk about my take on the current state of instruction sets in industry and the age-old “complexity of instruction set” question.

Visiting Prague

Over Easter, I took a short trip to Prague with parts of the family. It is a fascinating place – full of tourists and tourist businesses, but still feeling informal and homey. We tried to climb as many towers as we possibly could and visited a ton of sights in a few intense days.

Berlin – Cold War, Third Reich, and Ukraine

A few weeks ago I visited Berlin. A fantastically interesting city, and much more affordable and accessible than places like New York or London. However, it is almost comical how much of what you see ends up being about either the Third Reich or the Cold War and the DDR. The war in Ukraine was also noticeably present.

USS Massachusetts and Battleship Cove

I recently made a trip to the US to look at some interesting things like the USS Intrepid, the architecture or New York City, and Battleship Cove. Battleship Cove is located in Fall River, Massachusetts, and hosts the South Dakota-class battleship USS Massachusetts. Additionally, the site holds the destroyer USS Joseph P Kennedy, the submarine USS Lionfish, and the East German missile corvette Hiddensee. Given that I only had an afternoon there, I ended up only looking at the battleship with a brief run through the submarine. It was that good, especially in company with an old friend who also had read up on how the ship worked.

Code to the Spec(trum) or the Implementation

When writing software that uses any kind of API or hardware functionality, sooner or later there will be questions about what a particular API call or hardware operation is supposed to do. In principle, such questions should be answered by referring to the specification (and user documentation). I am a firm believer in writing readable and clear specs and keeping software coding to follow the spec, as that ensures future compatibility. But reality is not that simple. Things are generally better today than they used to be, though. Reading up a bit on the history of my first computer (the ZX Spectrum), I found some rather interesting cases of spec vs implementation, and “discovered functionality”.

Thank You, Sir Clive Sinclair

A few days ago, Sir Clive Sinclair died. I owe him, or rather his most successful product, my career as a computer scientist. I bought myself a ZX Spectrum in my early teens, taught myself how to program it, and never looked back. The ArsTechnica obituary calls the Spectrum a “gaming computer”, and I guess that is mostly fair. Can’t say I ever used it for more than playing games or programming games.

Timesharing System Design Concepts (1970)

When I recently turned 50, a friend of mine gave me a book that was about as old as me – Timesharing System Design Concepts, by Richard W Watson. The copyright date is 1970, but the publishing date found online 1971. The book covers the hardware support and software techniques needed to provide multiple users with simultaneous access to a computer system. Typically, using remote teletype terminals. It is a wonderful book, reflecting on the state of computer technology around 1970. It shows both how many of the basic concepts we still use today were already in use back then, but at the same time just how far we have evolved computing since.

Oljeön – The World’s Oldest Preserved Oil Refinery

With Covid-19 still a bit of an issue, the summer of 2021 is yet another one for “svemester” (Sverige-semester, or Sweden-vacation). There are plenty of things to see, and one place that I finally got to visit was the old oil refinery at Oljeön in Ängelsberg, home to Engelsbergs oljefabrik and the world’s oldest preserved oil refinery dating back to the mid-1870s. It is a beautiful piece of industrial history, well-preserved and with good guided tours.

View of Oljeön from the mainland. The refinery is the yellow building on the right, the darker building on the left is the one remaining oil storage shed

Professor Reinhard Wilhelm on the History of WCET Analysis

Back when I was a PhD student working on worst-case execution-time (WCET) analysis, one of the leading groups researching the topic was the “Saarbrücken gang” led by Professor Reinhard Wilhelm. Last year, Professor Wilhelm published a retrospective look on their work on WCET in the Communications of the ACM. It is a really interesting history write-up from the perspective of the Saarbrücken group.

The First Swedish Programmer (1790s)?

The history show (and podcast) of Sverige Radio, Vetenskapsradion Historia, is one of the shows that I subscribe to and listen to regularly. In their look back at 2020, they reminded me of an episode from back in the summer that indirectly introduces what I believe to be the first programmer in Sweden.

Hemsö Fästning – Coastal Defense from the 1950s

Continuing on my blog posts about our Hemester (part 1 covered Bodens Fästning), this blog post will cover Hemsö Fästning. Both are fascinating places, but also rather different, and clearly demonstrate the changes from the early 1900s to the Cold War of the 1950s.