Welcome to PCjs, the first IBM PC simulation to run in your web browser without any plugins. It was added to the JavaScript Machines project in Fall 2012, and is now part of the PCjs Project on GitHub. The project includes:
- PCjs, a simulation of the original IBM PC (circa 1981)
- C1Pjs, a simulation of the OSI Challenger 1P (circa 1978)
All the simulations are written entirely in JavaScript. No Flash, Java or other plugins are required. Supported browsers include modern versions of Chrome, Safari, Firefox, Internet Explorer (v9.0 and up), Edge, and assorted mobile browsers.
The simulation above features an Intel 8088 running at 4.77Mhz, with 64Kb of RAM and an IBM Monochrome Display Adapter. For more control, there are also Control Panel and Soft Keyboard configurations, featuring the built-in PCjs Debugger. For even greater control, build your own PC. The PCjs Documentation will help you get started.
The goals of the JavaScript Machines project are to create fast, full-featured simulations of classic computer hardware, help people understand how these early machines worked, make it easy to experiment with different machine configurations, and provide a platform for running and analyzing old computer software.
Some pre-configured machines are shown below, ready to run BASIC, DOS, Windows 1.01, and assorted non-DOS software.
Check out the rest of the PCjs Application, Boot Disk and Machine demos, including an IBM PC Dual Display System demo of multiple monitor support, and IBM PC XT "Server Array" and Windows 1.01 "Server Array" demos of multiple machines running side-by-side.
Below is the OSI Challenger C1P, another simulation in the JavaScript Machines project. It simulates Ohio Scientific's 6502-based microcomputer, released in 1978. More details about this simulation and the original machine are available in the C1Pjs Documentation.
The PCjs repository on GitHub contains everything needed to run PCjs computer simulations. The PCjs and C1Pjs emulators run in any modern web browser, with or without a web server, and examples are provided for both local and remote operation.
The project includes:
- A simple Node-based web server (server.js)
- Custom Node modules used by the web server (HTMLOut, MarkOut, DiskDump, FileDump)
- A variety of IBM PC and C1P configuration and resource files (see /apps, /devices and /disks)
- The PCjs and C1Pjs client applications, both "compiled" and uncompiled
- A smattering of PCjs and C1Pjs documentation, along with blog posts, related publications and more
The bundled web server is not strictly required. Any web server (Node, Apache, Nginx, etc) that can serve the necessary JavaScript files to your browser will work. However, instructions for doing that are beyond the scope of this introduction.
In fact, you can run PCjs simulations without a web server at all, using the "file:" protocol instead of "http:". However, most of the machine configurations require additional resource files (ROMs, disk images, etc), which are included in the project, but unless all the resource files are moved into a single directory (as they are in these Demos), your browser will probably be unable to load all of them, due to security restrictions. Using the bundled web server is the preferred solution.
The project includes a large selection of disk images, and a powerful DiskDump utility that runs on both the client and server, featuring a command-line interface (CLI) and web server API. Originally created to dump existing disk images as JSON, DiskDump has evolved into a full-featured disk image generator, capable of creating PC-compatible diskette and hard disk images from either lists or directories of files (including all subdirectories).
The following instructions were originally written for OS X. However, users of other operating systems should have no problem following along. There are some prerequisites:
- Node with NPM (download an installation package for your OS from nodejs.org)
- Git (included with OS X Developer Tools; separate download required for Windows)
Some additional (optional) tools are also recommended:
- Python (included with OS X; separate download required for Windows)
- GitHub (useful for getting Git set up on Windows; also available for OS X)
Once you have the prerequisites, open a command-line window, cd to the directory where you'd like to install PCjs,
and type the following commands:
git clone git@github.com:jeffpar/pcjs.git pcjs
cd pcjs
npm install
node server.js
Now open a web browser and go to http://localhost:8088/. You're done!
If you just want to launch the web server or don't plan to do any development, you can reduce the footprint slightly by asking NPM to install only "production" modules (which can also eliminate some errors if, for example, you neglected to install Python):
npm install --production
If you ever inadvertently run npm install without --production, you can easily uninstall all the
"devDependencies" listed in package.json with this command:
npm prune --production
Finally, when installing on an AWS server, although you have complete control over how Node is launched, you don't have direct control over NPM; I think the best you can do is set the following AWS "Environment Property":
NPM_CONFIG_PRODUCTION=true
The current version of Node (0.10.32 at the time of this writing) should work fine, but version 0.10.26 is what's been used to develop and test PCjs so far.
Also, server.js was originally written using Express v3. Since then,
Express v4 has been released, but the npm install command above will make sure that v3 is installed locally.
The plan is to eventually move development to a newer version of Node, and migrate the PCjs server to a newer version of Express; there's no desire to remain stuck in the past (well, ignoring the fact that PCjs is the quintessential "stuck in the past" project), but there's also no urgency to update.
Unlike a typical project, where you have to build or configure or make something, PCjs is "ready to run". That's because both the compiled and uncompiled versions of PCjs are checked into the project, making deployment to a web server easy.
However, in order to build and test PCjs modifications, you'll want to use Grunt and the Grunt tasks defined by Gruntfile.js.
Although Grunt was installed locally when you ran npm install, you'll also want to install the command-line
interface to Grunt. You can install that locally as well, but it's recommended you install it globally with -g;
OS X users may also need to preface this command with sudo:
npm install grunt-cli -g
Now you can run grunt anywhere within the PCjs project to build an updated version. If no command-line arguments
are specified, grunt runs the "default" task defined by Gruntfile.js; that task runs Google's
Closure Compiler if any of the target files (eg, pc.js or pc-dbg.js
in the /versions directory) are out-of date.
To ensure consistent compilation results, a copy of the Closure Compiler has been checked into the /bin folder. This version of Closure Compiler, in turn, requires Java v7 or later. Use the following commands to confirm that everything is working properly:
java -version
which should report a version >= 1.7; eg:
java version "1.7.0_67"
Java(TM) SE Runtime Environment (build 1.7.0_67-b01)
Java HotSpot(TM) 64-Bit Server VM (build 24.65-b04, mixed mode)
Then run:
java -jar bin/compiler.jar --version
which should report:
Closure Compiler (http://github.com/google/closure-compiler)
Version: v20150609
Built on: 2015/06/09 16:35
If you don't have Java installed, it's recommended that you install the JDK (not the JRE), because the JRE may not update your command-line tools properly. Note that Java is used only by the Closure Compiler; none of the PCjs client or server components use Java.
Newer versions of the Closure Compiler should work as well, and at some point, a newer version will be checked into the project.
The PCjs web server is little more than a file/directory browser for the PCjs project, plus a collection of APIs.
If a URL corresponds to a PCjs project folder and no "index.html" exists in that folder, the server loads an HTML template (common.html) and generates an "index.html" for that folder.
The contents of the "index.html" will vary depending on the contents of the folder; for example, if the folder contains a README.md, then that file is converted to HTML and embedded in the "index.html". Similarly, if the folder contains a machine XML file, that is embedded as well.
The PCjs client app can also be run from the command-line mode using Node, making it possible to script the application, run a series of automated tests, etc:
cd modules/pcjs/bin
node pcjs
The pcjs script in modules/pcjs/bin loads all the PCjs browser scripts listed in the root package.json and then starts a Node REPL ("read-eval-print loop"). The REPL handles a few special commands (eg, "load", "quit") and passes anything else to the PCjs Debugger component. If no Debugger component has been created yet, or if the Debugger didn't recognize the command, then it's passed on to eval(), like a good little REPL.
Use the "load" command to load a JSON machine configuration file. A sample ibm5150.json is provided in the bin directory, which is a "JSON-ified" version of the machine.xml displayed on the pcjs.org home page.
The command-line loader creates all the JSON-defined machine components in the same order that the browser creates XML-defined components. You can also issue the "load" command directly from the command-line:
node pcjs --cmd="load ibm5150.json"
In fact, any number of "--cmd" arguments can be included on the command-line. A batch file syntax will eventually be added, too.
When PCjs runs in a browser, an XML machine configuration file is transformed into HTML with a set of DIVs for each component: an "object" DIV whose data-value attribute provides the initialization parameters for the corresponding component, along with a set of optional "control" DIVs that the component can bind to (eg, a "Run" button, or a visual representation of DIP switches, or whatever).
When PCjs is run from the command-line, there is no XML, HTML, or DIVs involved; this is basically a "headless" version of PCjs, so there is no simple way to view a machine's video display or interact with its keyboard, mouse, etc. You have to use Debugger commands to dump the machine's video buffer.
Since I was not inclined to add XML support to my Node environment, this has created some divergence between client and server operation: PCjs on the client supports only XML machine configuration files, whereas PCjs on the server supports only JSON machine configuration files.
I haven't decided whether I'll add support for JSON configuration files to the client, or add some XML-to-JSON conversion to the server, or both.
To help test/debug changes to PCjs server components (eg, DiskDump, HTMLOut), you can start the server with some additional options; eg:
node server.js --logging --console --debug
The --logging option will create a node.log that records all the HTTP requests, --debug
will generate additional debug-only messages (which will also be logged if --logging is enabled), and --console
will replicate any messages to your console as well.
If you want server.js to use a different port (the default is 8088), set PORT in your environment before starting the server:
export PORT=80
or add --port to your command-line:
node server.js --logging --console --debug --port=80
A complete list of command-line options can be found in server.js.
A special command parameter ("gort") can be appended to the URL to request uncompiled client source files, making PCjs and C1Pjs much easier to debug, albeit much slower:
http://localhost:8088/?gort=debug
The "gort=debug" command is unnecessary if the server is started with --debug; the server always serves uncompiled
files when running in debug mode.
Conversely, if the server is in debug mode but you want to test a compiled version of PCjs, use:
http://localhost:8088/?gort=release
and the server will serve compiled JavaScript files, regardless whether the server is running in debug mode or release mode.
Another useful gort command is "gort=nodebug", which is like "gort=debug" in that it serves uncompiled files, but it also sets the client-side DEBUG variable to false, disabling all debug-only runtime checks in the client and allowing the simulation to run much faster (although not as fast as compiled code):
http://localhost:8088/?gort=nodebug
Regrettably, the gort command "Klaatu barada nikto" is not yet recognized. Fortunately, there are no (known) situations where PCjs could run amok and destroy the planet.
Other parameters that can be passed via the URL:
- autostart: set it to "true" to allow all machines to start normally, "false" to prevent all machines from starting, or "no" to prevent all machines from starting unless they have no "Run" button.
For example:
http://localhost:8088/?gort=debug&autostart=false
To start developing features for a new version of PCjs, here are the recommended steps:
- Change the version number in the root package.json
- Run the "grunt promote" task to bump the version in all the machine XML files
- Make changes
- Run "grunt" to build new versions of the apps (eg, "/versions/pcjs/1.x.x/pc.js")
You might also want to check out the blog post on PCjs Coding Conventions.
You may also want to skip step #2 until you're ready to start testing the new version. Depending on the nature of your changes, it may be better to manually edit the version number in only a few machine XML files for testing, leaving the rest of the XML files pointing to the previous version. Run "grunt promote" when the new version is much closer to being released.
In the course of testing PCjs, there may be stale "index.html" files that prevent you from seeing application updates, changes to README.md files, etc. So before running Node, you may want to "touch" the default HTML template:
touch modules/shared/templates/common.html
The HTMLOut module compares the timestamp of that template file to the timestamp of any "index.html" and will regenerate the latter if it's out-of-date.
There's a TODO to expand that check to include the timestamp of any local README.md file, but there are many other factors that can contribute to stale "index.html" files, so usually the safest thing to do is "touch" the common.html template, or delete all existing "index.html" files, either manually or with the Grunt "clean" task:
grunt clean
The PCjs Project is now an open source project on GitHub. All published portions are free for redistribution and/or modification under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
You are required to include the following copyright notice, with a link to http://pcjs.org:
PCjs © 2012-2015 by Jeff Parsons (@jeffpar)
in every source code file of every copy or modified version of this work, and to display that notice on every web page or computer that runs any version of this software.
See LICENSE for details.
Learn more about the JavaScript Machines Project and PCjs. To create your own PCjs machines, see the Documentation for details.
If you have questions or run into any problems, feel free to tweet or email.