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.
Tag Archives: Ibm
IBM Mainframe: Parallelism as Patch
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.
Virtual Platform by Virtualization Extensions — 1969
By means of a trip down virtualization history, I found a real gem in 1969 paper called A program simulator by partial interpretation, by Kazuhiro Fuchi, Hozumi Tanaka, Yuriko Manago, Toshitsugu Yuba of the Japanese Government Electrotechnical Laboratory. It was published at the second symposium on Operating systems principles (SOSP) in 1969. It describes a system where regular target instructions are directly interpreted, and any privileged instructions are trapped and simulated. Very similar to how VmWare does it for x86, or any other modern virtualization solution.
David Ditzel Interview at The Register/Semicoherent Computing
The Register has a few podcasts in addition to their website, and the one called “Semicoherent Computing” has turned into a very nice series of interviews with interesting people from the computer industry. I recently listened to their interview from September 2007 with David Ditzel of Transmeta fame. He had a lot to say about the history of computing, as well as interesting things on where computing is going. Well worth a listen! Particular interesting highlights…
IBM z6: Multicore, Accelerators
The IBM mainframe family started with the S/360 back in the 1960s is still going strong. The naming has been a interesting in recent years, going from S/390 to z900 to z990 to z9.
Solaris to IBM, x86 to Apple, Power to Microsoft, and other flying pig events
The register report “IBM embraces – wtf – Sun’s Solaris across x86 server line” is a very appropriate headline for something quite surprising. The day before this happened, we discussed the announced announcement and said “nah, it can’t be about operating systems”. The idea of IBM in-sourcing Solaris for x86 just felt like the kind of thing that was in the same realm as flying pigs, freezing hells, and similar unlikely events.