Emulator

! How to install SIMH PDP-8 emulator?

Legacy Installer

May 17, 2023 • 4 min read

In this tutorial, we will install the SIMH PDP-8 emulator. The PDP-8 was a minicomputer produced by Digital Equipment Corporation as part of the PDP series.

Installing

Linux

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If you have not already installed a Linux distribution, see our tutorials on how to install Kubuntu, a beginner-friendly distro.

Installing from source code

Like other emulators of SIMH family, the recommended way to install it is to compile it from source code. First, we need to install some tools and dependencies to build it. On Ubuntu/Debian based distros, run the following command:

sudo apt install git make gcc libpcre3-dev libedit-dev libpng-dev

On Fedora and related distros, run:

sudo dnf install git which make gcc pcre-devel libedit-devel libpng-devel

On openSUSE and related distros, run:

sudo zypper in git which make gcc pcre-devel libedit-devel libpng16-devel

On Arch based distros, run:

sudo pacman -S git which make gcc pcre libedit libpng

Now, move to the Downloads folder and clone the SIMH repository:

cd ~/Downloads

git clone https://github.com/simh/simh.git

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The simh/simh repository uses a non-free license. You may want to use open-simh/simh repository instead. To know the difference between the two, see here.

git clone https://github.com/simh/simh.git

Move to the simh folder:

cd simh

Run the following command to start compiling emulator:

make pdp8

It will take some time to compile, depending on your hardware. When it is done, move to the BIN folder:

cd BIN

We will install the executable in /usr/local/bin so that we can call it without specifying its path:

sudo install pdp8 /usr/local/bin/

Enter your password when asked to do so.

We have installed the SIMH PDP-8 emulator. Now you can start it. Just run this command:

pdp8

Install from distribution repository

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The last stable release of SIMH was very long time ago. Most distributions continue to package it. It may or may not work with the VirtualHub tutorials. The best way to install SIMH emulators is from source, as explained above.

Some old versions of SIMH don't read pdp8.ini file directly. If you are facing that problem, use pdp8 pdp8.ini instead of simply pdp8 when following VirtualHub tutorials.

PDP-8 emulator is available in Ubuntu repositories in simh package. You can install it on Ubuntu and any Ubuntu/Debian based system using the following command:

sudo apt install simh

This will prompt you for your password. Enter it. The simh package will install. Now you can run PDP-8 emulator:

pdp8

Many other distributions also package simh. On Fedora based distros, you can run sudo dnf install simh. On openSUSE based distros, it is sudo zypper in simh. For Arch and related distros, you can use sudo pacman -S simh.

These distributions rename the executable in their packages. So you would need to run simh-pdp8 to start the emulator instead of pdp8. Modify the VirtualHub tutorials accordingly if you install it via this method.

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On Arch based distros, you can install simh-git from the AUR. This will install SIMH from the latest git snapshot and is much recommended instead of the regular simh package.

Conclusion

That's it. We installed the SIMH PDP-8 emulator. Now you can follow the tutorials on VirtualHub which uses this emulator.

To exit the emulator, type exit and press enter.

Windows

You can download a set of all SIMH emulators from this repository. Extract the archive. Inside, you will find another archive. Extract it. Inside, you will find several executable. Move the file named PDP8.exe to somewhere (if you have added some folder to the PATH environment variable previously, you can move the PDP8.exe file to that folder).

Now add the folder where you moved the PDP8.exe file to the PATH environment variable. To do so, open the Start menu and search for the Edit the system environment variables entry, which opens up a System Properties window. In the Advanced tab, click on the button Environment Variables. There you’ll see User and System variables, which you’ll be able to edit.

In the section entitled User Variables, double-click on the entry that says Path. Another window will pop up showing a list of paths. Click the New button and paste the path to your PDP8.exe executable there. Once that’s inserted, select your newly added path and click the Move Up button until it’s at the top.

That’s it! You may need to reboot your computer for the changes to take effect, but you should now be able to call pdp8 from the command line:

To exit the emulator, type exit and press enter.

Documentation

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These PDFs may be outdated. You will find the latest version of the documentation (in .doc format) in the doc folder of the git repo you cloned.

Credits

Video tutorial

Do you want to follow the tutorial by watching a video? Here it is:

Archives of this tutorial are available on Wayback Machine.

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