Fifty Years Ago IBM 'Bet the Company' On the 360 Series Mainframe

Hugh Pickens DOT Com (2995471) writes "Those of us of a certain age remember well the breakthrough that the IBM 360 series mainframes represented when it was unveiled fifty years ago on 7 April 1964. Now Mark Ward reports at BBC that the first System 360 mainframe marked a break with all general purpose computers that came before because it was possible to upgrade the processors but still keep using the same code and peripherals from earlier models. "Before System 360 arrived, businesses bought a computer, wrote programs for it and then when it got too old or slow they threw it away and started again from scratch," says Barry Heptonstall. IBM bet the company when they developed the 360 series. At the time IBM had a huge array of conflicting and incompatible lines of computers, and this was the case with the computer industry in general at the time, it was largely a custom or small scale design and production industry, but IBM was such a large company and the problems of this was getting obvious: When upgrading from one of the smaller series of IBM computers to a larger one, the effort in doing that transition was so big so you might as well go for a competing product from the "BUNCH" (Burroughs, Univac, NCR, CDC and Honeywell). Fred Brooks managed the development of IBM's System/360 family of computers and the OS/360 software support package and based his software classic "The Mythical Man-Month" on his observation that "adding manpower to a late software project makes it later." The S/360 was also the first computer to use microcode to implement many of its machine instructions, as opposed to having all of its machine instructions hard-wired into its circuitry. Despite their age, mainframes are still in wide use today and are behind many of the big information systems that keep the modern world humming handling such things as airline reservations, cash machine withdrawals and credit card payments. "We don't see mainframes as legacy technology," says Charlie Ewen. "They are resilient, robust and are very cost-effective for some of the work we do.""

The Mythical Man-Month

[Peter Simpson]

Should be required reading for anyone planning to manage a large engineering project. It's full of tips that can save you from significant embarassment. If you're not managing a software development project, at least make sure your boss reads it. If your boss has *already* read it, he might be worth working for.

Re:Not really all that important in the big pictur

[L. J. Beauregard]

If you work for a large company, chances are a mainframe prints your paycheck.

If you work for a small company, they probably outsource their payroll to some company such as Paychex, and a mainframe still prints your paycheck.

Re:It also killed innovation

[Required Snark]

The IBM Stretch had an early form of out of order execution. This was in 1959.

http://people.cs.clemson.edu/~mark/stretch.html [clemson.edu]

Amdahl discussed his original idea for lookahead with John Backus "two or three times". "And John thought what I had proposed initially, he couldn't do a compiler for. So we went ahead and redid it. And we came out with the thing that was the look-ahead structure of the STRETCH." [p. 71, Norberg]. Amdahl recalls that "principally the look-ahead pre-fetched instructions to see branch instructions early enough so that we could get the succeeding instruction and data for each of the two alternative branch paths"

The CDC6600 a more advanced form in 1964.

http://en.wikipedia.org/wiki/Out-of-order_execution [wikipedia.org]

Arguably the first machine to use out-of-order execution was the CDC 6600 (1964), which used a scoreboard to resolve conflicts. In modern usage, such scoreboarding is considered to be in-order execution, not out-of-order execution, since such machines stall on the first RAW (Read After Write) conflict. Strictly speaking, such machines initiate execution in-order, although they may complete execution out-of-order.

From the same source:

About three years later, the IBM 360/91 (1966) introduced Tomasulo's algorithm, which made full out-of-order execution possible.

Re:software

[thoriumbr]

Looks like you know nothing about mainframes and "aged technology". I work with mainframes. zVM, DASD, DirMAINT, RACF and other buzzwords are in my resume, along with Linux, Java, PHP, XML, jQuery, MariaDB, HTM5, Eclipse and others.
Mainframes are not aged technology. They are perceived as such by small companies and people. Big companies with big bucks know a lot about mainframes. They know mainframes are the most reliable hardware platform on the market today, and I guess it will continue as so for a couple of years, because mainframes were made from the start to be reliable. Other platforms got they reliability implanted on them. Mainframes were designed reliable and resilient.
Mainframes today runs Linux too, not only the "aged mainframe operational systems." And here we have mainframes running hundreds of Linuxes with jBoss. They are about to be orchestrated by OpenStack, so managing all this "aged technology" will be done in brand new Android and iOS tablets.

Job prospects in my area, at least for the next decade, are very good. Half the openings in my area are still open, paying for a intermediate zVM administrator almost twice what a senior Java programmer or MCSE will receive. And there's no people applying!
But if the mainframe job market have a problem, is lack of people. Mainframes are not user friendly, and youngsters are not likely to devote two or three years learning something from the grannies, on a very harsh learning environment, with a step learning curve, when all their peers are talking about creating a new app and selling to Google for a gazillion dollars.
Peer pressure is a greater force than job prospects. I faced this pressure when I talked to my peers that I was learning mainframe and everybody laughed at me. Now I earn 3 times what they do, and I am training some of them to work with me.