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I've inherited an antique computer with 64MB of RAM. I'd like to install emacs, but only if it will run. The emacs manual doesn't seem to have any system requirements listed. In fact, general searching only turned up the original's then extravagant 1MB RAM requirement and the joke that emacs stands for '80MB and constantly swapping.'

While larger RAM is on the way - 128MB - it would be nice to know whether to wait or not without having the system shudder to a halt.

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Ah, but you could use vi... <insert emacs vs vi holy war here>. – Zoredache Jul 21 '11 at 7:04
A very pertinent piece of information would be what OS you're planning to run (and also whether you want to run emacs in a console or GUI window). These constraints will significantly affect the memory requirements. – Handyman5 Jul 21 '11 at 7:15
That's quite the history piece you are inheriting. I'm a youngin. I started with the IBM ATs with(gasp) a 20MB harddrive. Be jealous. – surfasb Jul 21 '11 at 23:12

You should be good to go as long as you don't go overboard with the plugins and all that. Also, you should note that 'back in the day' the joke was "Eight Megabytes and Constantly Swapping" so once again you should be fine. Just for reference, I opened up an instance of emacs on my computer (The GUI version, that is) and it is only using about 7.5 MB of RAM. Worst comes to worst and it is too memory hungry for your computer, you can always uninstall it.

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Emacs 21.4 on RHEL 5.2 takes 117M of virtual memory, 10M of resident to start without X.

Emacs 23.1.1 on RHEL 6.1 takes 238M of virtual memory, 13M of resident to start, again without X.

Both of them were built with assorted X toolkits though.

My guess, if you make an ok sized swap partition AND don't mind waiting a bit while it starts up, you'll be happy.

If you build it yourself you might want to ask it to build without the X toolkits (GTK, Xaw3d, whatever), and maybe without X when you run configure.

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Emacs is a fairly old piece of software, from around 1976, so I would assume you would be fine putting it on your computer depending on what other software you have running simultaneously. I have an imac with 128mb of ram that I was able to get emacs working on flawlessly while doing other tasks and using screen. Though you temporarily have half the ram, you still should be fine. If worst comes to worst and your system does crash you can just reboot.


Likewise I can find no information on the current system requirements of the newest version of EMacs (March 10, 2011).

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I never had any trouble with various emacsen from major version 17 through major version 19 on a 64 MB powerbook or a 80 MB linux laptop, nor with major version 21 on a linux box with 128 MB. I've never tried a more modern versions in a tight memory situation.

However, emacs in not just an editor it is a way of life and its own operating system. The more modes you activate and the more buffers you keep open, the more memory it is going to sit on.

A useful command for low memory situations is kill-buffer in a standard installation it is bound to C-x k.

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