As a young software engineer, I often hear other colleagues talk about the days of punch cards and "computers as big as the room."

The earliest memories of computers that I have involve MS DOS and Windows 3.1.

My question is, are there still any companies, academic centers, or government agencies that still use mainframes from the 1960s-70s in their daily operations?

If so, can you think of a place that would allow visitors to observe such a machine at work? I know that there are several museums out there that possess such pieces, but I cannot think of a functioning one.

  • 1
    Are you talking about actual 40 year old hardware? Because I think you won't find too many of those still in use. Most companies will upgrade hardware as and when required and the OSs - particularly on the IBM front have been updated at regular intervals in the meantime.
    – temptar
    Aug 17, 2011 at 14:04
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    As a note, you can buy modern 'mainframes' from IBM, the Z series. Iirc, you can configure them so as to run software written for OS/360. Aug 17, 2011 at 17:31
  • My school had a computer history museum and many of the pieces were still functional including hardware integrated with teletypes and several that were programmed by loading words based on toggle switch position. Also had an analog computer. Got to program on most of them. Actually still in use? Scary to hear some of these answers...I guess if it works and it's stable...
    – Rig
    Feb 2, 2012 at 15:47

8 Answers 8


NASA at the very least. The retired space shuttles ran the same computer programs and equipment from initial commission. If I remember correctly, they had about 32K of RAM.

The reason they did this was that the software and hardware was known to be bug free, upgrading or changing equipment/software might have introduced life threatening bugs or have been prohibitively expensive to produce to such a high degree of bug free-ness.

  • 2
    Actualy they did upgrade the Shuttle computers: en.wikipedia.org/wiki/Space_Shuttle#Flight_systems but to the main point, yes they would still be considered archaic even after the upgrade.
    – sdg
    Aug 17, 2011 at 14:44
  • ISTR they have some old hardware (PDP-6s, maybe?) that they can't get rid of because it's an integral part of a deep space tracking network and has custom hardware that allegedly can't be replaced with modern hardware (I assume for financial reasons).
    – TMN
    Aug 17, 2011 at 15:23
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    There are a lot of PDP11s running traffic lights. There was a local company that made a PC card that emmulated a PDP11 to allow for upgrades Aug 17, 2011 at 16:09
  • The first SSD I ever saw emulated an RM05 after DEC stopped making those disks. This was probably in the early 90s, and was easily ten times faster than the original equipment. Probably extended the useful lives of hundreds of PDP-11s and other UNIBUS-based systems.
    – TMN
    Aug 17, 2011 at 21:39

The business of our company (a car rental company) is based on a mainframe, originally installed in 1972. There is no signs of it being replaced in the near future - it would cost an enormous sum of money and several years of effort.

One of my previous employers (an airline company) also had a mainframe as the backbone of its operations. They started to work on its replacement a couple of years ago, but I don't know where they are currently.

So yes, there are lots of them still in use, especially at banks. Since typically these run business critical systems, without which the whole company shuts down, they are tucked away in safeguarded data centers. Therefore, unfortunately I don't think they accept visitors from the outside world in most of these places.

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    However, do these organizations actually run this software still on the same 1970s hardware? I'd have thought that most would have replaced the hardware with newer but compatible models. Aug 17, 2011 at 14:37
  • @Michael, good question. It is still basically the same software, but I agree with you that they have probably upgraded the hardware since then. Aug 17, 2011 at 14:40
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    Heh, I remember reading about how NORAD did its satellite tracking using a mainframe that was emulating a 3083, which ran software that emulated a S/370, which ran software that emulated a S/360, which ran software that emulated a 709, which ran the actual program. I may have the model numbers wrong, but it was definitely at least four levels of emulation.
    – TMN
    Aug 17, 2011 at 15:28
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    @TMN: This kind of thing is going to become more and more commonplace. I'm sure there are lots of organizations running old MS-DOS business software on emulators, and running any 32bit apps on a 64bit OS basically involves an emulation layer as well. Aug 17, 2011 at 15:56
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    Generally the software is moved to newer hardware. Mainframe OSes run on layers of visualization so it's perfectly possible to run a 60s OS unchanged in a slot on a brand new mainframe. Mainframes makers are very big on backwards compatibility! Aug 17, 2011 at 16:03

The State of Michigan driver's license system still runs on a 1970s mainframe.

  • 7
    That explains the ugly picture that got printed on my driver's license.
    – oosterwal
    Aug 17, 2011 at 19:00
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    @oosterwal I'm not sure this explanation is wholly the fault of the mainframe system. Aug 18, 2011 at 16:50
  • @oosterval, mainframe printing systems are quite capable of modern graphics.
    – user1249
    Aug 18, 2011 at 17:04
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    oosterwal made a joke. Aug 18, 2011 at 20:11

A lot of air traffic control systems use Univac systems.

  • 2
    Yep, and I've seen a PDP11 running in an ATC centre.
    – Steve
    Aug 17, 2011 at 14:35

As far as software goes, sure. IBM, at least, has put a LOT of effort into maintaining upward compatibility. There's business logic that's still happily being used by a lot of large organizations.

As far as hardware goes, probably not:

  1. The older systems are slow, and consume a lot of power, and consume a lot of air conditioning (or water cooling). A newer system of equivalent power costs much less to run; the hardware replacement costs are dwarfed by the power/cooling/space that's not used by the replacement.
  2. There aren't many parts available for the older systems. Even when there are spares, it's going to be less expensive to replace an older system than fix it. The older the system is, the truer this is.
  3. There are few people left to fix the older systems. The manufacturers (e.g., IBM) don't maintain them any more, and I doubt anybody's even offering training in how to maintain/repair the older systems.

Economically, it doesn't make sense to run hardware that's that old. Replacing it with newer (but software-compatible) hardware costs less, and gives you a system that's more reliable and more maintainable.

However, economically, it does make sense to run software that's that old, if the business logic is still valid. (But that's a whole other conversation.) So, yes, there are an awful lot of business still running software that was written that far back.


When I was working at RAF Filingdales in the mid 90's, on the Ballistic Missile Early Warning System there, we were told that they couldn't directly connect anything but the original mainframe to the radar array, as it would be considered a violation of a strategic arms treaty governing the use of the early warning radar system.

I'm not now convinced that this was true, given the current National Missile Defence upgrade, but the original CDC-Cyber mainframe could still be in use if the NMD project has not yet been completed.

Certainly RAF Filingdales is not somewhere you should expect to get into legally without government vetting, though you could always join the CND instead. *8')

Given my doubts, I have created a question on skeptics: Are the computers connected to missile early warning systems limited by international treaty?.

  • Thge classic golf balls got torn down recently and replaced with a fancy new phase array radar. Technically the upgrade was in breach of the SALT but since the only people with the power to complain (USSR) had gone away it didn't matter. Which does raise the question of why they needed the upgrade ! Aug 17, 2011 at 16:07
  • it's impossible to ask a question on skeptics without it being closed. Logically any question that belongs on skeptics is pretty much always closeable as not a question/no answer possible! It's a bit of a logical wossname.... Aug 18, 2011 at 16:12
  • @Martin - It hasn't been closed yet and I've been getting as many up votes as down votes, so there's some chance. If it gets an answer or even a comment that the claim is notable enough (given the frivolity of some other questions which are allowed to stand) then it might even stay open. *8')
    – Mark Booth
    Aug 18, 2011 at 16:30
  • @MartinBeckett - That fancy new PAVE PAWS phase array radar was already there when I was installing a White Box NextStep machine to do offline analysis on the data. Funny to think that we were using Mail.app before OS.X was even conceived.
    – Mark Booth
    Dec 13, 2011 at 0:51

You can watch a Zuse Z3 in the museums in Munich and Hünfeld, Germany. It's the first fully functional, program controlled (freely programmable) computer of the world.


At my current company we are still using IBM TPF mainframes (several of them, given our performance constraints).

We are in the process (and have been for at least the 4 years I have been there) of migrating toward Linux-based boxes (swarms of them) with Oracle/MySQL/SQlite DBs (depending on the requirements).

It's a long and energy consuming task, but the mainframes are at their limits, and it would require buying even bigger/newer mainframes to replace them.

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