Esoteric Operating Systems: The History of OS/360 and its successors

Author's Note: First of all, I know this is going to be a case of tl;dr for most people, but a hell of a lot of work went into this. Apart from a whole load of research, I spent a week trying to install and use OS/360 MVT in order to get a feel for what computing was like in the 1960s, so I do know some of what I'm talking about when it comes to OS/360. Trust me when I say: That shit is hard, and the sort of work that went into it was far beyond the scope of most computer users.

Secondly, it's not a perfect piece. There are probably a few too many tangents off towards other computers and operating systems, but I was making a chronicle of a series of forty-five year-old operating systems which defied the odds several times to still be used today. It may not be the most riveting read in the world, but please at least give it a go. Comments will be very much appreciated, because I really did put a huge amount of work into this, and as I said, this goes far beyond the scope of most of the members of these forums in terms of difficulty.

Finally, if you're actually interested in emulating an IBM mainframe, you can try the Hercules emulator, which is capable of emulating System/370, ESA/390 and zArchitecture mainframes. Keeping this maintained is what Tron Guy does in his spare time. Doesn't say much good about me, I suppose - this is most likely why I haven't got a girlfriend. I need to get out more.

Esoteric Operating Systems - OS/360 and its successors

In 1964, IBM was the largest computer manufacturer in the world. Thomas Watson Jr. had brought the company forwards from mechanical tabulators to the electronic era, despite his father's initial objections, and the company had gained much success with its 700/7000 series of scientific computers, the 605 model, which opened up computer access all around the United States, and the 1401, their highly-successful business model. But despite this success, IBM found itself at a risky position. The computer models that IBM sold at that time were incompatible with each other, and customers were reluctant to upgrade because of the cost of moving over their programs and data.

The market needed standardisation, and IBM decided to risk its place at the top of a volatile computer industry, where many other companies had already failed, to design a standard system architecture which would serve businesses and scientists alike.

The venture was a success. IBM introduced the System/360 into the market in 1964, cementing its place at the top of the market with hundreds of new customers, who were ensured of the ability to expand as they needed. With a system architecture which would become the standard in mainframes up to the present day, IBM managed to sweep many of its competitors from the market, establishing itself as the industry leader for years to come.

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This picture might look a bit odd to some people. I mean, when is the last time you saw a programmer wearing a suit?

System/360 machines were highly sophisticated for their time, with some of the earliest hard disc drives providing megabytes of storage and near-instant access to data where competing machines only had the sequential data storage of magnetic tape. For such an elaborate system to be used correctly, it required an equally elaborate operating system. Operating systems were a relatively new innovation, allowing for easier input/output routines without the necessity of programming them in for every program, and IBM had used them itself for some of its previous computers.

So, IBM planned two operating systems for its System/360 machines: OS/360 for punch-card batch processing, and the more advanced TSS/360 for time-sharing on more powerful System/360 computers. Both operating systems ran into development trouble, with TSS/360 never being released at all, but it was the development of OS/360 which became the most infamous.

Fred Brooks, one of the developers of the System/360 and project leader of the OS/360 project, released a book in the 1970s detailing some of the problems which had developed during the protracted development of the operating system. Named The Mythical Man-Month, the book noted some very important concepts in operating system design. This included an argument against the eponymous Mythical Man-Month, where more man-power was thought to be beneficial to a software project, with Brooks proving that "adding more man-power to a late software project makes it later".

The most relevant of these concepts, however, happened to be Brooks' description of the so-called "second-system effect", where IBM went from a series of small, efficient operating systems on their 700/7000 series to a large, late operating system on the System/360 in an attempt to include features that they had forgotten in previous projects. As a result of this, OS/360 ended up as an extremely bloated OS for its time, requiring a lot of memory and expensive system resources at a time when programmers had to be highly efficient. Unfortunately, this principle has struck again in several later projects, including those by Microsoft (who are probably up to fourth-system effect by this stage!).

Because of the high system specifications to run OS/360, IBM were forced to produce a second batch-processing system, named DOS/360 (for Disc Operating System, and not to be confused with the personal computer DOSes). This operating system lacked the co-operative multitasking of OS/360, but was compatible with the lower-end business System/360 computers. Other interim measures existed with the BOS/360 (Basic Operating System) and TOS/360 (Tape Operating System) lines, but DOS/360 was the only one of these operating systems which became popular.

When OS/360 was finally released in 1966, it finally gave the System/360 the multiprogramming support that it required. However, the operating system was designed for computer specialists, with a language known as JCL (Job Control Language) inherent to the structure of the computer, designed for the computer to process quickly. OS/360 was not an easy operating system to use, made for punch-card input and programming languages like COBOL and FORTRAN, with teams of perhaps a dozen programmers, keypunch operators and other technical staff.

As part of my research for this article, I installed an OS/360 MVT system on the Hercules emulator. OS/360, along with its successors, and the DOS/360 line as well, uses JCL, a language used for simple system tasks. The only problem is that it isn't too simple to use.

Whereas a copy file interaction under Unix would be performed like this:

cp <1stFile> <2ndFile>

the corresponding JCL for OS/360 looks something like this:

//IS198CPY JOB (IS198T30500),'COPY JOB',CLASS=L,MSGCLASS=X
//COPY01 EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//SYSUT1 DD DSN=OLDFILE,DISP=SHR
//SYSUT2 DD DSN=NEWFILE,
// DISP=(NEW,CATLG,DELETE),
// SPACE=(CYL,(40,5),RLSE),
// DCB=(LRECL=115,BLKSIZE=1150)
//SYSIN DD DUMMY

Er, right. I don't think I'll bother learning JCL, then.

Few computers at the time were any easier to use, with the first successful minicomputer only designed in 1961, but these computers, usually present in universities or small computing companies, were able to be programmed and operated by a single person. While the microcomputer revolution of the late 1970s and 1980s was still a long way away, the atmosphere around these more simplistic machines, including the TX-0 and TX-2 in MIT's Lincoln Labs, and the recently produced DEC PDP-1, was far more lax than that around the huge, complicated and expensive System/360s, to the point where the famous Sketchpad digital drawing program and even the seminal and groundbreaking computer game, Spacewar!, could be developed on it.

In contrast, the stuffy atmosphere around IBM's machines contributed to a slightly oppressive opinion of them, and the languages that were used with them were derided by many of the early hackers for their inelegant syntax. There was no room to experiment with a System/360, because their programs demanded accuracy. What is more, the social changes of the 1960s were creating a new generation of computer scientists, ones with more relaxed clothing styles and social mores than their predecessors, who programmed with full suits and ties.

Meanwhile, as TSS/360 was cancelled due to even more protracted development than OS/360, replacement time-sharing systems were being programmed elsewhere. TSO (Time Sharing Option) gave users of the MVT variant of OS/360 a limited amount of time-sharing ability, and while this option would not become widely adopted by IBM's business customers, who usually only required batch processing, it was more appreciated by scientists and military customers.

At the same time, IBM's Cambridge Scientific Centre were developing a native time-sharing operating system. Running on the System/360-67 variant of the architecture, CP/CMS was a lightweight operating system specifically designed with scientific time-sharing in mind, and was built with an easier interface than the difficult OS/360. It wasn't officially supported by IBM, being distributed under an open-source model to those places that desired it, mainly scientists rather than business customers.

By 1970, the success of the System/360 had easily paid for the risks undertaken and the protracted development of OS/360, and had helped IBM squeeze some of its rivals out of business. From the 1960s, where the mainframe producers had been colloquially named "Snow White and the Seven Dwarfs", IBM had produced a situation where rivals sold out their mainframe businesses at the hands of System/360's market dominance. Now, the mainframe manufacturers were called "IBM and the BUNCH", the "BUNCH" taking its name from the first letters of the smaller manufacturers.

But things were not perfect for IBM. Incensed at the loss of the MULTICS project to General Electric, IBM needed to develop a new architecture in order to stay competitive. (However, in ironic circumstances, General Electric would be forced to sell out their mainframe business to Honeywell in the late 1960s, and MULTICS would become a laughing stock as it was succeeded by a private project produced by Dennis Ritchie in Bell Laboratories.) So, with the developments made on System/360 in mind, IBM developed its successor, System/370. With the new innovations of integrated circuit design and support for virtual memory included, among other improvements, System/370 became more sophisticated than its predecessor, yet retained complete backwards compatibility with all of its code and even its operating systems.

This architectural improvement helped IBM to maintain its position at the top, and yet, unknown to them, the seeds of the demise of their core business had just been sown. One of these factors would be caused by a company co-founded by Robert Noyce. Noyce, who had been one of the "Traitorous Eight" who had split off from Shockley Semiconductors, home of the transistor, had decided to make his own way once more, founding a company called Intel. In 1969, an Intel team led by Ted Hoff had invented the microprocessor, the first fully-integrated "computer on a chip", and this invention would have far-reaching consequences as discussed later, ones which would change the face of computing forever.

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Intel's 4004 microprocessor led to a complete change in computing.

The other two factors in 1970 that would begin to erode IBM's huge lead went hand-in-hand. The first was the rising prominence of the minicomputer, particularly in universities. DEC, developers of the PDP-1, had found much success with other PDP models, and while IBM had a few products present in this market, they failed to pay them much attention. The second factor was an operating system which just happened to be programmed on one of these PDP computers.

Developed in Bell Laboratories, Unix was an operating system first programmed in 1969 by Ken Thompson on a PDP-7 computer, and it had already swept aside the MULTICS project. Unix was just a pet project of Thompson, but it had several factors which would strongly influence later and even modern operating systems. Most important of these was the revelation that a high-level (human-readable) programming language could be used for operating systems, which would allow for Unix's portability across system architectures. But there were more innovations which would help to cement its later success among computer scientists. Even from the very start, it had full pre-emptive multitasking, which made it perfect for time-sharing, and some of its design briefs would prove instrumental in helping it avoid much of the second-system effect and bloat of operating systems such as OS/360 and MULTICS.

Neither of these factors, however, would start to show their relevance until later on. System/370 came into being having to account for three major lines and a few minor lines of operating system from its predecessor, and so, each of these lines was brought forward with new variants. The low-end DOS/360, originally designed as a stop-gap, became DOS/VS. CP/CMS would eventually become VM/370 (Virtual Machine). IBM failed to account for the potential success of this operating system, which became very popular within the scientific market, partially for its abilities to virtualise itself perfectly, proving one of the very first uses of an emulator.

OS/360 had two specific variants to take account of. The less elaborate MFT variant was replaced by OS/VS1, while the more sophisticated MVT variant was replaced by OS/VS2, better known as MVS/370 (Multiple Virtual Storage). Unlike the development of OS/360, the development of the System/370 operating systems went quite smoothly, particularly as the code could be tested on System/360 machines using CP/CMS.

With these operating systems, IBM would manage to see off its competitors during the 1970s as well, even with increasing pressure from DEC's PDP and VAX series minicomputers, many now running Unix, and the efforts of Cray Inc., who would build the most powerful supercomputers in the world until the late 1980s. But the seeds of change were germinating, and the microprocessor was coming into its own. The Motorola 6800, MOS Technology 6502 and Zilog Z80 would give cheap processors to those interested in designing their own computers, and after the successes of the MITS Altair 8800 and Apple I, a large number of companies entered the microcomputer market.

With companies such as Apple and Commodore selling millions of computers in America, and Acorn Computers and Sinclair Research doing the same in Europe, IBM realised that their market was at stake. Many of the traditional customers of mainframes would have no use for one with readily-available personal computers, and so, IBM would have to build a personal computer of their own if they wanted to remain relevant in the computing market.

Dispensing with normal in-house IBM design, a team was assembled to build a personal computer rapidly. Taking the Intel 8088 processor and using a form of BASIC from Microsoft, the company which had created the BASIC variant for the MITS Altair 8800, IBM produced the IBM 5150, better known as the IBM PC.

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The IBM PC 5150, predecessor of the PCs most people use today.

The IBM PC was a huge success. Appealing to business customers who had previously bought Apple and Commodore computers, the IBM PC lent huge legitimacy to the personal computer market and set the standard for personal computers to the present day. But while IBM had once again maintained its strong position as the largest computer manufacturer in the world, its mainframe business appeared to be increasingly obsolete, with little need for huge water-cooled, room-sized machines when personal computers could do many of the same things businesses had already been doing more easily and for less cost. What's more, because the IBM PC was based on a commercially-available processor rather than one designed by IBM in house, the IBM PC's BIOS was soon reverse-engineered, leading to a huge number of clone systems.

Nevertheless, IBM designed a new mainframe architecture, designated ESA/390, at a time when workstations were obtaining amounts of RAM only found in mainframes before then, and when IBM's position in the personal computer market looked increasingly weak from competing clone manufacturers. The problems with operating systems had long been solved, with time-sharing available across the whole range, and several releases of MVS and VM through the lifespan of the System/370. ESA/390 had an astounding level of backwards compatibility, able to run programs from the very beginning of the System/360's lifespan.

About halfway through the life of ESA/390, suddenly, there became a resurgence in the level of mainframe use. Spurred on by companies discovering new uses for their mainframes, and a general shift in IBM's tactics, which led to their adoption of open-source operating systems, the mainframe defied odds to survive right through the 1990s. New operating systems were devised to maintain the three lines developed during the late 1960s. MVS was updated to become OS/390, which adopted many modern operating system concepts, while VS/370 became VSE. The VM line, which had been largely ignored during the 1960s and 1970s by IBM, became more important as users increasingly supported thousands of users on their mainframes. But to supplement these three lines, IBM's new committal to open-source led to its adoption of Linux, usually used in conjunction with other operating systems on the same machine.

Today's mainframe is much different to the mainframe of 1964, on the introduction of the System/360. Apart from the far superior power of today's machines, they are used according to completely different paradigms. The mainframe of 1964 usually used batch processing using punch cards and magnetic tape, and some of them didn't even have the ability to perform more than one task at a time. Today's mainframe is usually used by hundreds or thousands of people at a time, through Web interfaces, and its power is in high potential input/output rates and extremely high reliability.

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A System z10 machine, large, hugely reliable and capable of serving hundreds of people at once.

IBM is still the world's largest manufacturer of mainframe computers, holding 90% of the market with their System z line of mainframes. Linux is gaining an increasing share of use on these mainframes, not often the main operating system on the mainframe, but becoming more popular. The three lines of operating systems from the 1960s still remain, with z/OS the successor of the OS/360 line, z/VSE the successor of DOS/360 and z/VM replacing the CP/CMS project. Each of these operating systems has adopted large amounts of modern computing concepts, yet maintain extreme backwards compatibility. The COBOL code of the 1960s, written for machines using punch cards and teletypes, will still work with little or no modification today.

However, IBM is no longer the largest computer manufacturer in the world. Removed from the desktop computer market by the pressure of clone manufacturers who left IBM unable to compete, and eventually selling out their line of high-quality but expensive Thinkpad laptops to the Chinese company, Lenovo, IBM now focuses on other markets, from its server and supercomputing lines, to the development of the POWER processor, most recently used in the consoles of today. Hewlett-Packard, only a humble calculator manufacturer in 1964, is now the largest computer company in the world, and one of the largest companies altogether.

The mainframe might not have the glamour of the supercomputer, or even the appeal of a desktop computer, but it performs tasks today that are essential to our society. The operating systems for the IBM mainframe, despite their difficult start, have matured into stable platforms, ready for huge loads every day, and ones able to run programs that are forty years old when today's desktop operating systems often have difficulty with ten-year-old programs. There are lessons to be learned even today from the OS/360 project, particularly with the idea of the second-system effect (something Microsoft is guilty of several times), but despite the difficulties experienced during its development, it has maintained its line during a time period where dozens of operating systems and computer platforms have died out, and that is something to be impressed with, regardless of your ultimate position on the future of the mainframe.

A bit on the technical side for me, maybe, but very very interesting. I didn't know there was that much development during the 60's. Now I feel all kinds of stupid.
I for one don't mind when you head of on some details as I love a text that sprawls a bit. I'm not proficient enough in English to comment on the language beyond that I found it good for the type of article.
I think I might wanna look into all this old computing stuff. Can you recommend any good books, apart from the one already mentioned, to get me started? If any books even exist chronicling the early computing?

Not too long for me. I read the whole thing. Superb work, start to finish. It reads with tremendous polish, and I don't mind the slight branching-off every so often at all. In fact, going down side roads probably works to your favour.

I can only see one shaky part, here:

RAKtheUndead:
About halfway through the life of ESA/390, suddenly, there became a resurgence in the level of mainframe use.

The word suddenly has a place here, but not where you've put it. I think that:

About halfway through the life of ESA/390 there arose a sudden resurgence in the level of mainframe use.

Would flow a little more cleanly. Otherwise, spectacular work, and I do feel like I've learnt something from reading it.

History and computers, 2 of my favourite subjects, very interesting to read. The differences between current command line OS and JCL was really interesting, as Im currently learning to use Linux.

Great article. The obvious research is much appreciated. It's nice to see so much effort thrown into something. From the perspective of one not overly well-versed with computers, this is simple enough to understand while still challenging me. The diction does not condescend which is fantastic.

Where do you see the technology going from here? Smaller, perhaps, but other than that?

teh_gunslinger:
I think I might wanna look into all this old computing stuff. Can you recommend any good books, apart from the one already mentioned, to get me started? If any books even exist chronicling the early computing?

A lot of general-purpose computing books from the 1980s, right about the onset of the business personal computer, would have a section devoted to computer history, and there are certainly books which specialise in chronicling the early days of computers. I can't think of any off-hand, but I know that I have a few of them at home.

As well as that, as maligned as Wikipedia may be as a research tool in some areas, it is an exceptional tool when researching things related to computers. Not all of the pages are particularly readable, but it does give a very good grounding in computer history.

WeedWorm:
History and computers, 2 of my favourite subjects, very interesting to read. The differences between current command line OS and JCL was really interesting, as Im currently learning to use Linux.

The thing was that JCL wasn't even command-line stuff back when it started, as command line interactions were limited to responding to system messages. You had to write it onto punch cards using a keypunch, and you'd wrap it around the source code you wanted to compile.

There are presumably much easier alternatives these days, but that 1960s JCL made even the earliest forms of Unix look easy. (Today's command-line Linux is usually much cleaner and better-documented.)

Labyrinth:
Where do you see the technology going from here? Smaller, perhaps, but other than that?

Actually, after the mid-1990s, the mainframe became a much smaller system than it had been before, no longer needing much of the specialist air-conditioning or water-cooling that it had needed prior to that. As for where mainframe technology is going to go, because mainframes are all about extreme reliability even under heavy load and huge amounts of input/output performance, I presume that they'll go for increasingly multi-core processors, and as soon as solid-state memory becomes viable and reliable for years at a time, that will be an obvious step forward, with its superior read/write performance and its lack of moving components.

Whether they'll survive indefinitely all depends on the technological advances in server technology, which has the advantage of being more flexible and less centralised, but which typically needs a larger space and more cooling equipment to have the same performance as a mainframe.

Very interesting and well-written article.

i cried the day IBM gave up their desktop business, simply put they had the hands down best support of any company i've dealt with, they would NEVER fight with you, they would at the most suggest something else and if you disagreed with it, they would go with your suggestion

as for their servers they are rock solid and great, the only downside compared to Dell is you have to piece it together and funnily enough i have a pdf of the study dell commissioned to show it's better cause you can install the Dell rack server faster because it comes preassembled for you, so all you have to do is take it out of the box and slide it into the rack

I've never heard of that operating system.

Quite a long read, still quite interesting. Very impressive amount of text, there. Obviously you put a lot of work into it. I never know anything about mainframes, let alone IBM's operating systems. Now I know.

I always wonder why todays server cases always make them look like they are going to launch me out an airlock and lock the pod-bay doors :/

Good article, RAK.

Great work! I would footnote your sources and write a bibliography.

Multi processing on a mainframe? 2 core 1972 or so. 4 core model 3084 in 1983. 6 core by 1989. Up to 64 cores in a single mainframe with the z10.
Software VM, 1969 (CP/CMS) Hardware VM (partitioning), 1992

Oh, how many monitors do you have hooked up to your PC? Mainframe often support hundred to 10 thousand or more users do work.

Lovely article, well done.

Just a couple of comments of course. :-)

The example JCL vs Unix 'cp' command is a little unfair on JCL. In JCL, the copy program might be better compared to the Unix 'dd' command. 'dd', like most Unix commands has many, many options - example being the type of disk I am writing to/from, the blocksize to use, etc. The JCL copy example shows these types of 'optional' specifications coded - thus making it appear more complex than necessary.

My other issue was with the statement:

"little need for huge water-cooled, room-sized machines when personal computers could do many of the same things businesses had already been doing more easily and for less cost"

In the early days of personal computing (the first company I worked for bought an 8086 and let me play - we were a traditional 'mainframe shop' at the time), the 'toy' computers, as we called them, could do very little of practical benefit to the main business operations. Instead, we thought up new uses for these devices - mostly in desktop publishing and prototyping of software intended to run on the mainframe. We invented new uses for computers - like everyone else did eventually. The real challenge to the mainframe came when the PC's became small office servers, then with the advent of standardised networking over TCP/IP, clusters of PC's could start to deliver real business processing.

The 'problem; of the mainframe has always been it's huge upfront capital cost. Why buy a mainframe, when a few 'cheap' servers might do the trick. This attitude was exacerbated by the pushing of IT costs away from a centrally managed service (the IT Dept), and out into the business units of companies - these units could not afford a mainframe, so went with what they could afford. This proliferation of smaller systems, once they became business critical, then was foisted back on the central IT Dept to manage the resulting sprawl. This is where the IT industry is at today - sprawl management. This has led to out of control costs in most datacentres - and while mainframes may be expensive up front, you know what you're getting and what it will cost you over 10 years or more. That isn't the case with servers, and thus the true cost of server computing is well hidden amongst the racks of other kit you also need to buy.

One more statement I think deserves comment:

"Each of these operating systems has adopted large amounts of modern computing concepts"

The truth is completely the reverse. IBM pioneered most of the advanced processor techniques used in modern Intel and other CPU's. Ideas of caching, pipelining, pre-fetch, pre-emptive execution and many more all came from mainframes and were later added to small CPUs. IBM pioneered Virtualisation with CP/CMS, now z/VM - that's 40 years of virtualisation experience. I remember when Microsoft introduced Systems Managed Storage - IBM had been doing HSM (Hierarchical Storage Manager) for 20 years by then - and they'd encountered all the problems SMS also eventually encountered, and found solutions, most of which were re-invented and hailed as revolutionary by SMS fans 20 years later!

I just love the way this industry goes in circles.

You mention the legendary backward compatibility of the mainframes - yes, it really is amazing. I have run 30 year old programs on a brand new mainframe without even having to re-compile them. No other operating system in the world guarantees this - and again, this is part of the cost efficiency of the mainframe. How much does it cost your server based business to re-write or at least re-compile EVERY single line of code every 3-5 years!

Sorry my comment is so late on your post - I just found your article today mentioned in a newsgroup that I do follow. Now I'm signed up here as well - hope some more interesting stuff like this comes along.

Cheers - Mike

PS: I work for IBM, as a software specialist. For 23 out of my 25 years in IT, I have worked for other companies.

Very nice and well-written article. Must've took a while to write it all.

I've bookmarked this because I want to read it again and again, Rak you are superb, I really admire what you've done.

mcairns:
Sorry my comment is so late on your post - I just found your article today mentioned in a newsgroup that I do follow. Now I'm signed up here as well - hope some more interesting stuff like this comes along.

Sometimes I end up forgetting that the internet is so expansive, so I find myself surprised when people find my articles from other sources. Not that I'm complaining - it's nice to get some recognition, and I'm glad to see that the article wasn't rubbished by people who have more experience than I do with the IBM mainframe operating systems.

The article does have a few flaws, and I'll acknowledge that the first PCs couldn't even begin to compete with the mainframe as a platform, but they did undercut the minicomputer, such as IBM's System/32 and System/34, somewhat, even if the PC was only a single-user system with a "toy" operating system. I suppose that the "killer apps" for the personal computer ended up being the word processor, the spreadsheet and the database program, rather than anything that the mainframe may have specialised in, but it did end up invading the office eventually.

In terms of other articles along these lines, I did write another article in the Esoteric Operating Systems series before this, concerning RISC OS. If I get time - university has left me short of time to play with computer systems - I'm thinking of writing an article on BeOS as well. Thanks for the acknowledgement, of course, and I'm glad to see people still enjoying the article.

mcairns:
Lovely article, well done.

Lovely article, wonderful reply.

I hope to see more of your hands on knowhow, marvelous stuff.

I wish I didn't have such a short attention span, anyway, I better get back to playing bioshock, you heard right! I put bioshock on pause so I could read Rak and Mike's contributions.

wow a car!

RAKtheUndead:

mcairns:
Sorry my comment is so late on your post - I just found your article today mentioned in a newsgroup that I do follow. Now I'm signed up here as well - hope some more interesting stuff like this comes along.

Sometimes I end up forgetting that the internet is so expansive, so I find myself surprised when people find my articles from other sources. Not that I'm complaining - it's nice to get some recognition, and I'm glad to see that the article wasn't rubbished by people who have more experience than I do with the IBM mainframe operating systems.

The article does have a few flaws, and I'll acknowledge that the first PCs couldn't even begin to compete with the mainframe as a platform, but they did undercut the minicomputer, such as IBM's System/32 and System/34, somewhat, even if the PC was only a single-user system with a "toy" operating system. I suppose that the "killer apps" for the personal computer ended up being the word processor, the spreadsheet and the database program, rather than anything that the mainframe may have specialised in, but it did end up invading the office eventually.

In terms of other articles along these lines, I did write another article in the Esoteric Operating Systems series before this, concerning RISC OS. If I get time - university has left me short of time to play with computer systems - I'm thinking of writing an article on BeOS as well. Thanks for the acknowledgement, of course, and I'm glad to see people still enjoying the article.

I find the difference between RISC and CISC rather fascinating, isn't RISC what the PS3 does? and it does a fine job of it too. But modern PC's are CISC based?.

See stupid short attention span, I've got an IQ of 157 and I can't sit down long enough to bother with making myself better, I'm fucking rubbish.

To be fair no one uses IEBGENER in this way any more.. they are more likely to use FASTCOPY or another more user friendly program that doesn't require you to specify the size. Plus you can always just copy a file simply from a TSO panel.

I'm no fan ZOS, I've worked in IT departments on Wall St. for the last 10 years so I know my way around ZOS and distributed systems. If I had my way we'd use the IBM mainframes as doorstops and switch everything to Solaris or AIX. Though at least you can run zLinux (SUSE) on z10's nowadays..

You were right! It is incredibly esoteric and too long!

RAKtheUndead:

Very interesting read.
Well written and very informative, nicely done.

 

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