Talk:Mainframe computer

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Contents 1 POV 2 Other Manufacturers 3 PDPs 4 Redundancy 5 Dumb terminals 6 Supercomputers 7 Mainframe language breakdown 8 Speculation on evolution of the word mainframe 9 Why did mainframes survive the predicted doom? 10 Performance 11 Origin of the word mainframe 12 capacity 13 Supercomputer vs Mainframe 14 Whu? 15 Too much POV 16 Other Mfg's 17 Reference for IBM mf 18 This article was written by IBM's marketing department 19 Is this computer, "xyz", a mainframe ?

[edit] POV

This seems like so much marketing material from IBM rather than a reflection of the current status of mainframes. The article needs to be heavily edited for balanced point-of-view, substantiated claims, references with a formal, neutral tone.—The preceding unsigned comment was added by 67.180.83.26 (talk • contribs) 23:22, 19 October 2006.

Fixed, see #Too much POV below. RossPatterson 02:43, 14 November 2006 (UTC)

[edit] Other Manufacturers

ICL should be included in the list of mainframe manufacturers and their 2900 series in the list of ranges. Wilmot1 02:55, 1 March 2007 (UTC)

[edit] PDPs

Some PDP's were mainframes.

Year  18-bitters     12-bitters             16-bitters                36-bitters

1960    PDP-1 ------------------------------------------------------------
1961      |                                                               \
1962    PDP-4 <--- LINC --------                                           \
1963      |        PDP-5   \    \                                           |
1964    PDP-7        |      \    \                                       PDP-6
1965      |        PDP-8 --\ |    \                                         |
1966      |        PDP-8/S LINC-8  |                                        |
1967      |          |       |     |                                     PDP-10 KA10
1968    PDP-9      PDP-8/I,L |     |                                        |
1969      |          |     PDP-12  |                                        |
1970    PDP-15       |           PDP-14    PDP-11(/20)                      |
1971      |        PDP-8/E                  /   |  \                        |
1972    PDP-15/76  PDP-8/M           PDP-11/05  |  PDP-11/45 --          PDP-10 KI10 
1973                 |             /   |       PDP-11/40  |    \            |
1974                 |            /    |            |     |     \           |
1975               PDP-8/A   PDP-11/03 PDP-11/04    |     |  PDP-11/70   PDP-10 KL10 
1976                 |                 PDP-11/34    | PDP-11/55  |          |
1977               VT78                   |    PDP-11/60         |          |
1978                                   PDP-11/34C            VAX-11/780  PDP-10 KS10

In a nutshell all the 36-bitters were mainframes and the rest weren't.

DEC pulled out of the mainframe business before completing the PDP-10 KC10 and jilted their whole mainframe customer base (including CompuServe and MCI/Tymenet) which marks the beginning of the end for DEC since many of those customers moved to UNIX not VMS where DEC couldn't pull the rug out from under them again. —The preceding unsigned comment was added by 66.92.164.43 (talk • contribs) 13:06, 21 December 2002.

[edit] Redundancy

Removed this:

The internal redundancy of these computers can be such that, in at least one reported case, technicians could move one from one site to another by disassembling it piece by piece, and reassembling it at the new site, whilst leaving the machines running. The switchover in this example took place entirely transparently.

I know this is in the Jargon File, but on reflection a better and more specific source would be nice. --Robert Merkel 05:11, 17 Feb 2004 (UTC)

On top of that, it's a bunch of malarkey. It just doesn't happen, and never has. RossPatterson 02:39, 14 November 2006 (UTC)

[edit] Dumb terminals

mainframes used non-"dumb" terminals, with some editing and form functionality in the terminal itself. in "dumb terminals" each keypress was transmitted to the host, which updated the display accordingly. the "dumb terminal" was coined in contrast to the terminals used before with mainframes that had more smarts. —The preceding unsigned comment was added by 213.139.167.121 (talk • contribs) 20:01, 5 May 2004.

Fixed. You're absolutely right - the 3270 family of terminals is anything but "dumb". RossPatterson 02:40, 14 November 2006 (UTC)

[edit] Supercomputers

comparison with supercomputers: basic idea: supercomputers are for compute tasks, mainframes are for reliability and io problems. actually the difference is pretty hard-and-fast one in my opinion. if you look at products marketed by suprecomputer companies and mainframe companies, you see at least the following differences: supercomputers are geared towards doing computations instead of organising data and shuffling around io. mainframes are engineered for reliability, availability and serviceablity. mainframes typically have relatively feeble cpu power compared to their contemporary high performance computing platforms. mainframes are designed to reliable transaction processing, whereas supercomputers are designed to churn through computative workloads with i/o systems fast enough not to bog down the computation business.

there is a saying: a supercomputer is a machine that converts an i/o bound problem to a compute bound problem.

sorry i'm not much good with producing wikipedia-quality article text.. —The preceding unsigned comment was added by 213.139.167.121 (talk • contribs) 20:17, 5 May 2004.

Nice job, it captures the essence very well. RossPatterson 02:42, 14 November 2006 (UTC)

[edit] Mainframe language breakdown

Where does the breakdown of programming languages used come from? I know that a lot of mainframe programming was done in Assembler, and much of that code is still out there being maintained. After Assembler, COBOL was popular, and probably is the most popular high-level language out in mainframe-land; but is it 90% of development? I doubt it. Nowadays, there is a lot of development in Java (especially on Websphere [which as far as I can tell is an IBM mainframe version of Apache], but also in CICS). C/C++ has been used for years (I know because I've done some). Then there are all the scripting languages: REXX, EXEC, CLIST, even JCL. —The preceding unsigned comment was added by 66.150.41.150 (talk • contribs) 18:28, 12 July 2004.

Got it from a bloke at work the other day who's been working on mainframes for 35 years, other than that i can't really justify the figure given. Even though a lot of the new code is in Java, i believe thats only because its enjoying its 15 minutes of fame. I guess the reason COBOL perseveres so much would be down to the 20 year nearly competition free spate it enjoyed as the main language on the mainframe. To this day a lot of changes and expansionon code on mainframes would be done in COBOL while they have the employees with the skills. The complexity of COBOL is not far off assembly, and i believe a direct descendant of tape code

If you think we should drop that statement i have no problem, i will try and get some firmer evidence later this week.Pluke 23:53, 12 Jul 2004 (UTC)

Have adjusted the figures accordingly from talking to some serious mainframe evangalists at work. Trying to find the figure for lines of new COBOL code written for mainframes each year, its supposed to be huge! Pluke 20:41, 14 Jul 2004 (UTC)

[edit] Speculation on evolution of the word mainframe

This is pure guesswork, but the use of the word to mean "big honkin' MIS computer" has always puzzled me. Here's my speculation. Comments welcome. I always used it to mean "the bay or bays containing the CPU in any floorstanding computer," and was annoyed one day when someone said "that's not what it means; it means a computer that costs more than a million dollars." Here's what I'm guessing took place.

• First, mainframe means "the bay or bays containing the CPU in any floorstanding computer."
• Third-party vendors of plug-compatible peripherals for IBM 360-series computers don't want to mention IBM by name, so start referring to IBM with the circumlocution "the mainframe vendor." Or, people need a neutral or indirect way to say "IBM and/or Amdahl." So the phrase "mainframe vendor" comes into use.
• Extrapolating from this use, "a mainframe vendor" is soon taken to mean "manufacturer of big honkin' MIS computers." Or "IBM and the seven dwarfs."
• One more cognitive step is needed, though, because IBM of course made computers of all sizes. So the next step is "mainframe" comes to mean "the kind of computer most commonly associated with IBM" = "big honkin' MIS computer."

Thoughts? [[User:Dpbsmith|Dpbsmith (talk)]]

The jargon file says the term refers to the systems' enourmous outer casing. --Apantomimehorse 08:34, 16 August 2006 (UTC)

That's exactly what he means. The "enourmous outer casing" is the "bay(s) containing the CPU". For example, the System/360 model 168-III's CPU covered a 250 square foot area, and each pair of I/O channels held down another 25 square feet of floor tiles. We'll probably never know, though. The jargon file is a lousy source in this case - it came from the opposing camp. RossPatterson 02:50, 14 November 2006 (UTC)

[edit] Why did mainframes survive the predicted doom?

They're big and they're very expensive, how come modern day servers with all their claims to be 'autonomic' and with their improved qualities of service, haven't killed the mainframe for good?

Is it just a case of it being too expensive and risky to transfer over to the servers that companies stick with mainframes?

Are there any scenarios that a company would move over to a mainframe solution from a server solution?

Any hard evidence to show the benefits of Mainframes over servers?

How long before they actually die out? --80.40.60.154 18:09, 20 Sep 2004 (UTC)

While I am not an expert on this, I believe there are a few factors. One is that mainframes tend to survive in places where speed of data access is critical. Mainframes can be designed to optimise data throughput, in a way that Intel boxes cannot be. Secondly reliability. One mainframe replaces several Intel servers; this basicly means fewer possible causes of failure. Thirdly, support. Again if one mainframe replaces many Intel boxes that's less maintenence work to do. Fourthly one stop shopping. If your IBM mainframe breaks, IBM will come and fix it for you. DJ Clayworth 18:19, 20 Sep 2004 (UTC)

One cannot ignore simple inertia and platform lock-in. COBOL is not as portable as most literatures makes out. Vendors have, over the years (given the extremely slow rate of change in standards... 1960, 1974, 1985, 2002) have implemented their own extensions. Companies with literally millions of lines of COBOL simply cannot take it off. Additionally, transactionality/unit of work management is important. Without an adequate and performant two-phase commit ability, slowly migrating systems away from the mainframe is difficult. One can think of the mainframe as a nail in the centre of a system, with attempts to migrate away being a rubber band fastened around the nail. Problems often mean that the path of least resistance (if not ultimately the optimal path) is still on the mainframe, being written in COBOL. 7 Jun 2005. —The preceding unsigned comment was added by 82.41.212.98 (talk • contribs) 16:42, 9 June 2005.

Highly unusual comment been added at the foot of the article, re: Unix having no standards, which is only partially true from the viewpoint of twenty years ago. Mainframe 'standards' are only based on the fact that they are proprietary and hence follow a 'standard' of sorts. A subtle comment indicating that there are 'no known viruses on the mainframe' it seems to me is intended to indicate some sort of design superiority over Unix/PCs/Windows etc. If it were that easy, everyone would be doing it. It seems to me there are various reasons why a virus is unlikely on a mainframe.

• They cost large sums of money (into the millions of dollars) to buy one; hence, hackers typically don't have one in their bedroom
• They operate on closed networks
• There is relatively little documentation on the OS

MetalMickey 20:07, 6 August 2005 (UTC)

A related question is "Why did the conventional wisdom come to believe that mainframes were doomed?" Wikismile 13:53, 12 August 2005 (UTC)

"Undoubtedly debates will continue about the mainframe's value ... The debate began with the 1964 introduction of the IBM System/360 and has continued for over 40 years." I don't recall any debate at all during most of this period. Even during the 1970s, minicomputers represented an expansion of computization rather than a threat to mainframes. Where is the evidence of such debates? --Wikismile 15:20, 26 October 2005 (UTC)

I worked for ICL in the late 1970's and 80's and I do remember debate taking place particularly after the first desktop microcomputers started to appear in the mid-eighties. Part of the reason why mainframes survive is the major costs involved in moving systems. If your system works don't fix it is the attitude. The costs involved in moving systems don't only include the relatively small costs of new hardware and software. They include converting data, retraining staff (particularly management) in the new systems, finding work-arounds for the stuff the old system did but the new system doesn't do. Wilmot1 03:06, 1 March 2007 (UTC)

[edit] Performance

Finally, I get to ask an encyclopedia a question. What sort of performance do mainframe computers have? CPU speed (GHz)? Number of processors? Number of MIPS? Quantity of memory? I know that there will be a range of values, but it would be good to see either a range of values or particular values for one mainframe type. Thanks. Mjm1964 16:41, 22 Jun 2005 (UTC)

Generally speaking, "mainframe" computers contain about the same speeds of processors as you'll see in other computers; everything is built out of the same ULSI semiconductor processes so the speeds and scales of the processors naturally fall out of that. One difference you will see is that certain processors (such as those used in the IBM z/OS computers) are actually internally-duplicated processors running in lockstep; if the two processors disagree on the results of a machine-language instruction, they fault it out to the service processor to figure out which one got it right,disable the one that got it wrong, call the Field Service Engineer, and then continue as if nothing had happened using only the non-faulted half of the chip. Such processors probably clock a little slower than your average bear, but they essentially never fail completely so the trade-off in speed is thought to be well worth it.

With regard to memory, mainframes tend to contain a lot of it but not many binary orders of magnitude more than is current at any given time. I'd guess that it tops out at several hundreds of GB right now. With regard to processors, it depends on the architecture and just what you're calling a mainframe. I *THINK* z/OS systems are still pretty low in processor count (8? 16?) while PowerPC-, Alpha-, and SPARC-based systems range up in the 128-1024 processor range.

If we were to include this sort of data in the article, I think we'd have to consider very carefully what represents a "mainframe" versus what represents a "supercomputer" versus what just represents a state-of-the-art big Unix server. If we're going to go down that route, I'd suggest that we use the IBM z/OS series as the reference point (and it's certainly well-enough described often-enough in editions of the IBM Journal of Research and Development that we could draw good, reliable data from there).

Atlant 18:28, 22 Jun 2005 (UTC)

I agree. z/OS is clearly the reference point. I think IBM are the only company making machines that run z/OS nowadays. IBM's big Unix machines do in many ways qualify as 'mainframes' in the sense that they've got a huge I/O capacity; however, I think the best definition of 'mainframe' is a machine that runs OS/360->z/OS. There's not really a scientific definition; the term is more an accident of history, rather than a well thought through definition. Incidentally, mainframes run a max of 256GB presently. It's also worth pointing out that these machines have been largely resilient to changes in thinking around what a good instruction set resembles, since they have to still run programs written for the first S/360 in 1964. MetalMickey 19:45, 23 Jun 2005 (UTC)

[edit] Origin of the word mainframe

I have searched the web for thirty minutes without finding the origin of the word mainframe. Am I the only person out here who knows where the word came from?

In an old electromagnetic telephone central office, each telephone number was associated with a given physical switch. Switches were all wired back to terminal blocks on a big rack. The incoming cables also terminated in terminal blocks on the same rack. Assigning a telephone number to a specific location, i.e., to the copper pair going to that location, was a matter of making a cross connect on this rack. The rack was called the "mainframe".

I don't know exactly how the word got transferred to large computers. I would suppose it came about because at least some of this computer equipment was mounted on standard racks, as was the equipment in a telephone office.

In 1968 in the signal school at Fort Monmouth, one day when we were working on rack-mounted computer components I referred to the rack as a "mainframe". Who out there can claim a computer-related use of the word earlier than 1968?

Joseph Mansfield, 14Aug2005, Jm546

See also 19-inch rack. Jm546 17:12:48, 2005-09-06 (UTC)

Odd, I've always been told (by 1940s to 1960s Bell Labs and Western Electric guys) that those things were called "crossbar switches", not "mainframes".RossPatterson 02:54, 14 November 2006 (UTC)

All of the above. See main distribution frame, telephone exchange, crossbar switch and panel switch Jim.henderson 01:25, 5 March 2007 (UTC)

[edit] capacity

How many terrabytes? Gazillion bytes?--Jondel 11:44, 21 October 2005 (UTC)

Three bajillion. RossPatterson 02:54, 14 November 2006 (UTC)

[edit] Supercomputer vs Mainframe

Is this correct? (One side effect is that even older software can benefit from adding mainframe CPs.) If so what does CPs mean? Or does it really mean CPUs?--Doc0tis 21:00, 23 November 2005 (UTC)

Yes, it's true. "CP" means "Central Processor", to distinguish it from the other processors that are often located on the slab of ceramic or silicon. CPs run the instructions of a program, just like what most other architectures call a CPU. Other processors do things like I/O handling, cryptographic primitives, or processing specialized workloads (databases, Java, etc.). But "CP" is definitely a term of art, so it's history in the article. RossPatterson 03:00, 14 November 2006 (UTC)

[edit] Whu?

What on earth is "[decreasing] Linux and Java processor prices by about 25%" meant to mean? --Fuzzie (talk) 02:27, 8 March 2006 (UTC)

Belated answer, but: IBM mainframes can be fitted with special-purpose processing units that are specific to Java, or to Linux. These units can't be used to execute mainframe software in general, only Java or Linux. (The limitation is enforced mostly by what PC folks would call firmware.) The big win is that software licenses are often priced in terms of the number of general-purpose processing units you have; so if you buy Java processors, or Linux processors, you can increase your capacity for Java or Linux without increasing the price of your other software. The special processors are also cheaper, even though they actually include more technology (not just a CPU, but also the stuff needed to limit your use of it). It's stupid, but that's the way the game is played.67.158.77.34 04:04, 6 November 2006 (UTC)

[edit] Too much POV

Give a careful read to this article, especially the point of view - so many sentences need to be rewritten but I dare not for fear of my own (relative) ignorance of mainframe computers. 71.116.217.242 20:25, 30 March 2006 (UTC)

I agree. The writer seems to be making an effort to be balanced, but it comes off awkwardly. There are too many qualifications, needless adjectives, and speculation ("...that strategy should help Unisys and HP improve their margins..."). A couple more examples:

• "... proven reliability, high-quality technical support, top-notch security..."
• "When discussing the mainframe market it's no exaggeration to say that IBM defines it."

This needs a rewrite by somebody familiar with the area. 24.60.149.101 (talk • contribs)

... proven reliability, high-quality technical support, top-notch security...

That's a true statement.

It very well may be, but the flourish of it sounds more like marketing than reference.--Tjkroh 16:06, 23 May 2006 (UTC)

When discussing the mainframe market it's no exaggeration to say that IBM defines it.

So is that.

Ibid.--Tjkroh

And I say this having no business relationship with IBM, now or ever. But "mainframe" really is still synonymous with IBM, z/OS, etc.

-Whether you have a relationship with them is irrelevant to the propriety of the tone. Don't get me wrong, it was an excellent article, and I enjoyed it a great deal, but it reads like a IBM brochure. It'd be nice to have a Unisys sympathizer give it a once-over to improve the balance.--Tjkroh

Atlant 13:00, 28 April 2006 (UTC)

Who's Unisys??? ;-)

Atlant 17:18, 23 May 2006 (UTC)

I have just completed a heavy edit on this article, and I believe it now accurately reflects the facts about mainframes and how they fit into the rest of the computing world. Feel free to carve on it and make it better. RossPatterson 02:27, 14 November 2006 (UTC)

[edit] Other Mfg's

I just Wanted to point out that Hitachi Data Systems, HDS was one of the main players in this industry for a very long time, and even toppled IBM for a while. It would be good to mention them. —The preceding unsigned comment was added by 24.20.186.59 (talk • contribs) 06:54, 13 July 2006.

If by "very long time" you mean 15 out of 45 years, yeah, it was, along with Fujitsu. But "toppled IBM"? Puhleeze. RossPatterson 03:02, 14 November 2006 (UTC)

[edit] Reference for IBM mf

Could use a scale-reference for this picture 69.28.40.34 19:52, 2 October 2006 (UTC)

The z890 is about the size of a common US refrigerator. Or maybe a Sub-Zero, but not much bigger. RossPatterson 03:04, 14 November 2006 (UTC)

That doesnt help people outside the US very much 130.246.132.26 13:30, 29 November 2006 (UTC)

[edit] This article was written by IBM's marketing department

I would strongly advise that this article be re-written. It is clearly a product of IBM's marketing efforts. There are numerous self serving statements about IBM being the leader in mainframe technology and an attempt to marginalise the competition. —The preceding unsigned comment was added by 70.27.199.213 (talk • contribs) 01:45, 3 October 2006.

Yeah, it sure reads like it. Fixed. RossPatterson 03:04, 14 November 2006 (UTC)

Still think Unisys need to sort their act out to steer some more truth in. IBM wasn't the first, and certainly not the best. More Univac/Sperry to show the lead and feature comparison of Burroughs/MCP vs IBM's AIX shows just how advanced the 'underdog' was. Also, do the Sun Fire 10k and 25k ystems count? —The preceding unsigned comment was added by 80.47.252.243 (talk) 00:54, 14 February 2007 (UTC).

[edit] Is this computer, "xyz", a mainframe ?

"Mainframe" might best be defined by example, list the 1st mainframes by the various manufactures. Were the early giants, ENIAC, AN/FSQ-7, ... mainframes? (if weight is the criteria, they're in!). —The preceding unsigned comment was added by 69.106.232.37 (talk • contribs) 15:03, 15 October 2006.

No, the Great Old Ones weren't mainframes. They were ... "computers". With cool names, like JOHNNIAC, SILLIAC, and GEORGE. And with the exception of the family of IAS machines, they were one-offs. The "mainframe" era usually starts with the IBM 704 or 7090, and the commercialization of the UNIVAC. RossPatterson 03:11, 14 November 2006 (UTC)