I attended a short Tech Tuesday morning session at IBM here in Kista, Sweden, where IBM presented their WatsonX-AI and related technologies. Tech Tuesdays is a monthly technical event organized by Kista Science City, where companies in Kista present some aspect of their technology in a 30-minute session. IBM managed to get an impressive amount of content into that time!
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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.
Continue reading “Timesharing System Design Concepts (1970)”CACM on DSAs
The July 2020 edition of the Communications of the ACM (CACM) had a front-page theme of “Domains-Specific Hardware Accelerators”, or DSAs. It contained two articles about the subject, one about an academic genomics accelerator, and one about the Google TPU. Hardware accelerators dedicated to particular types of computation are basically everywhere today, and an accepted part of the evolution of computers. The CACM articles have some good tidbits and points about how accelerators are designed and used today. At the same time, I also found a youtube talk about the first hardware accelerator, the IBM Stretch HARVEST, showing both contrasts with today as well as a remarkable continuity in concept.
Continue reading “CACM on DSAs”Simulation in the IBM ACS Project – Current Practices in 1966
I once wrote a blog post about the use of computer architecture pipeline simulation in the IBM ”Stretch” project, which seems to be the first use of computer architecture simulation to design a processor. After the ”Stretch” machine, IBM released the S/360 family in 1964. Then, the Control Data Corporation showed up with their CDC 6600 supercomputer, and IBM started a number of projects to design a competitive high-end computer for the high-performance computing market. One of them, Project Y, became the IBM Advanced Computing Systems project (ACS). In the ACS project, simulation was used to document, evaluate, and validate the very aggressive design. There are some nuggets about the simulator strewn across historical articles about the ACS, as well as an actual technical report from 1966 that I found online describing the simulation technology! Thus, it is possible to take a bit of a deeper look at computer architecture simulation from the mid-1960s.
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Hardware debug and measurement in the IBM POWER8
I have read some recent IBM articles about the POWER8 processor and its hardware debug and trace facilities. They are very impressive, and quite interesting to compare to what is usually found in the embedded world. Instead of being designed to help with software debug, it seems the hardware mechanisms in the Power8 are rather focused on silicon bringup and performance analysis and verification in IBM’s own labs. As well as supporting virtual machines and JIT-based systems!
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Fortress Rochester
In a dusty bookshelf at work I found an ancient tome of wisdom, long abandoned by its previous owner. I was pointed to it by a fellow explorer of the dark arts of computer system design as something that you really should read. The book was “Fortress Rochester”, written by Frank Soltis, and published in 2001.
IBM Mainframe: Parallelism as Patch
When IBM moved their mainframe systems (the S/360 family that is today called System Z) from BiCMOS to mainstream CMOS in 1994, the net result was a severe loss in clock frequency and thus single-processor performance. Still, the move had to be done, since CMOS would scale much better into the future. As a result, IBM introduced additional parallelism to the system in order to maintain performance parity. Parallelism as a patch, essentially.
IBM i – I’m Impressed
From what little I had heard and read, the IBM AS/400 (later known as iSeries, and now known as simply IBM i) sounded like a fascinating system. I knew that it had a rich OS stack that contained most of the services a program needs, and a JVM-style byte code format for applications that let it change from custom processors to Power Architecture without impacting users at all. It was supposedly business-critical and IBM-quality rock solid. But that was about it.
So when Software Engineering Radio episode 177 interviewed the i chief architect Steve Will, I was hooked. It turned out that IBM i was cooler than I imagined. Here are my notes on why I think that IBM i is one of the most interesting systems out there in real use.
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Pipeline Performance Simulator Anno 1960
I have just found what almost has to be the first cycle-accurate computer simulator in history. According to the article “Stretch-ing is Great Exercise — It Gets You in Shape to Win” by Frederick Brooks (the man behind the Mythical Man-Month) in the January-March 2010 issue of IEEE Annals of the History of Computing, IBM created a simulator of the pipeline for the IBM 7030 “Stretch” computer developed from 1956 to 1961 (photo from IBM.com).
Matt’s Today in History: System/360
I am a regular listener to the Matt’s Today in History podcast. When Matt asked for contributions for this spring (in order to meet a goal of 500 podcasts before Summer) I did give some thought to what I could contribute. Looking over some books, I found one suitable Spring date: the launch of the IBM System/360 back in 1964. The resulting podcast is now live at Matt’s Today in History.
Please be kind to any mistakes… I am trying to paint a broad picture for a computer-history-ignorant audience here.
Power Architecture Rip Van Winkle
For some reason (I guess it is the job…) I was browsing through the Power ISA version 2.06 specification last week and hit the following gem of an instruction: “rvwinkle“. It is named after a short story I had never heard about, but which apparently is sufficiently well-known in the US literary canon to warrant a sleep mode being named after it.
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IBM JRD Now Costs 1500 USD per Year
For the longest time, the IBM Journal of Research and development, and its entire archive, was online at IBM and for free to access. This publication was, I assume, seen as a way to publicize IBM systems and their research efforts. But now, it has unexplicable gone to a for-pay format. It costs 1500 USD/year to access it, which is pretty steep I think. Compare with sources like the Microprocessor Report, or regular IEEE or ACM memberships. I think this is a really dumb move, and I will miss reading their often quite interesting articles. Who will pay to read only about IBM systems and research?;
IBM z10 Heavy-Duty Virtual Platform
Unknown to most, IBM has one of the world’s longest records of using virtual platforms for software and firmware development and verification. This project has been ongoing since at least the days of the zSeries 900 machines, through z990, z9, and now z10. An excellent article on this virtual platform and its uses is found in the IBM Journal of Research and Development, number 1, 2009, . It is called “IBM System z10 Firmware Simulation”, by Körner et al.
Is Cycle Accuracy a bad Idea?
In a funny coincidence, I published an article at SCDSource.com about the need for cycle-accurate models for virtual platforms on the same day that ARM announced that they were selling their cycle-accurate simulators and associated tool chain to Carbon Technology. That makes one wonder where cycle-accuracy is going, or whether it is a valid idea at all… is ARM right or am I right, or are we both right since we are talking about different things?
Let’s look at this in more detail.
The 1970 rule strikes again: Virtual Platform Principles in 1967
Being a bit of a computer history buff, I am often struck by how most key concepts and ideas in computer science and computer architecture were all invented in some form or the other before 1970. And commonly by IBM. This goes for caches, virtual memory, pipelining, out-of-order execution, virtual machines, operating systems, multitasking, byte-code machines, etc. Even so, I have found a quite extraordinary example of this that actually surprised me in its range of modern techniques employed. This is a follow-up to a previous post, after having actually digested the paper I talked about earlier.
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