This is a server for the NABU Personal Computer. For more information about the NABU PC, please check out The NABU Network as well as Adrian Black's video about the NABU.

This server is written in C and is intended to be very portable to the Unix-like systems available today (the various BSDs, Linux, etc.) while also being as self-contained as possible, relying on no "external" software packages to build and run. The majority of the APIs it uses are either standard C99, standard POSIX, or extremely common extensions, for example some common BSD APIs that are also available in Linux, such as syslog(3) and daemon(3).

• Define up to 254 content channels (numbered 1-255) from an arbitrary number of sources.
• Sources can be local or remote (such as NabuRetroNet).
• Serve an arbitrary number of NABU PCs:
  • As many RS422 serial ports as you can connect to your system for real NABU hardware.
  • Support for connections from NABU emulators (such as MAME) over TCP.
• Decrypt and serve NABU pak files (available from NabuRetroNet).
• Serve your own or others' homebrew NABU binaries (nabu files).
• High-performance; nabud implements a content cache to optimize common access patterns and avoid redundant I/O.
• Small footprint; it can run on small machines. The only thing it throws memory at is the content cache.
• A control program, nabuctl, that allows a user to easily change the channel used by a NABU connection, select programs to load from homebrew channels (that vend ".nabu" files), view listings provided by such channels, etc.

nabud uses the GNU autotools-based build system that you're probably already familiar with, as it's used by many software packages. Most people will only need to do:

% ./configure
% make
# make install

nabud uses POSIX threads, which must be provided by your system.

In order to handle pak files, a cryptographic library is required; MD5 is used to generate pak file names and DES is used to decrypt them. The following cryptographic libraries are currently supported:

• CommonCrypto (the native API on macOS)
• OpenSSL's libcrypto. This is the native API already provided by many Unix-like systems, but you may have to go and install the "development" portion of the package in order to get the header files.

In order to download from remote sources, such as NabuRetroNet, an SSL library is required. The following SSL libraries are currently supported:

• SecureTransport (the native API on macOS)
• OpenSSL

On Ubuntu, the OpenSSL binaries and shared libraries were installed with the base system, but the header files were not. I installed them on my Ubuntu system like so:

% sudo apt update
% sudo apt install libssl-dev

Linux is, of course, extremely fragmented, so if you have some other distribution, getting OpenSSL installed is left as an exercise for the reader. Once it's installed, there is not likely to be any additional magic that you need to perform; the configure script will probably find it.

The nabuctl program has some basic command line history and editing support, provided by the libedit library on BSD systems. A compatible library may be available on other systems. I was able to install the development file for such a library on my Ubuntu system like so:

% sudo apt update
% sudo apt install libreadline-dev

Because an effort has been made to keep nabud fairly self-contained and reliant only on APIs provided by the operating system, building it just requires a toolchain. For the BSDs and Linux, it's probably already installed on your system, but if it's not, then doing so is left as an exercise for the reader. For macOS, you will need to install the Xcode Developer Tools and then launch Xcode to perform the "first launch" task that takes care of setting up the command-line tools that nabud uses to build.

Building on Cygwin is a little more complicated. In addition to the basic toolchain (gcc-core, binutils, make), you need to ensure you've installed the libssl-devel and libreadline-devel packages (make sure they match the versions of the run-time packages that are installed).

nabud understands the following command line options:

• -c conf -- specifies an alternate name / location for nabud.conf. The default location is $(prefix)/etc/nabud.conf.
• -d subsys -- enables debugging on the specified subsystem; see the nabud(8) man page for details. This option also implies -f.
• -f -- run in the foreground. Without this, nabud will detach from the controlling terminal and run as a daemon.
• -l logfile -- specifies the path to a log file. Without this option, nabud will log to the system log using syslog(3) using the LOG_USER facility. Note that when running in the foreground, log messages are always sent to the controlling terminal.
• -u user -- Specifies the user that nabud should run as.
• -U umask -- Specifies the file creation mask that nabud should use when creating files.

On macOS, nabud also understands the following command line options:

• -L -- runs nabud in "launchd mode". This is similar to the -f option, but does not change the logging destination.

On Linux, nabud also understands the following command line options:

• -S -- runs nabud in "systemd mode". This is similar to the -f option, but does not change the logging destination.

(Astute readers will note that macOS's -L and Linux's -S are the same.)

nabud requires no special permissions; only the ability to open files to be served to the NABU for reading, and the ability to open the serial ports for reading and writing. You can choose to run it as root or as a minimally- privileged user if you set the permissions on your serial port devices properly.

It is strongly recommended that you run nabud as a minimally-privileged user using the -u user option. Typically, you would do this by following these steps:

1. Create a group that will be able to modify any files created by nabud, for example nabu.
2. Create a user specifically for running nabud, for example nabu. Set the default group ID of that user to the group created in step 1.
3. Select a group that will be used to grant permission to open serial ports for NABU connections. Historically, a dialer or dialout group exists on some Unix systems for this purpose. Create one, if necessary.
4. Add the user created in step 2 to the group you selected in step 3.
5. Ensure your serial port devices grant read/write permission to the group selected in step 3.
6. Optionally use the -U umask argument to alter the default file creation mask so that users in the group created in step 1 can both read and write any files created by nabud.

For example, on my NetBSD system, I have the following user and group configuration for nabud:

% grep nabu /etc/group
dialer:*:117:nabu
nabu:*:2000:thorpej

% grep nabu /etc/passwd
nabu:*:2000:2000:NABU User:/nonexistent:/sbin/nologin

% ls -l /dev/ttyU*
0 crw-rw----  1 uucp  dialer  66, 0 Dec 31 14:15 /dev/ttyU0
0 crw-rw----  1 uucp  dialer  66, 1 May 19  2021 /dev/ttyU1
0 crw-rw----  1 uucp  dialer  66, 2 May 19  2021 /dev/ttyU2
0 crw-rw----  1 uucp  dialer  66, 3 May 19  2021 /dev/ttyU3
0 crw-rw----  1 uucp  dialer  66, 4 May 19  2021 /dev/ttyU4
0 crw-rw----  1 uucp  dialer  66, 5 May 19  2021 /dev/ttyU5
0 crw-rw----  1 uucp  dialer  66, 6 May 19  2021 /dev/ttyU6
0 crw-rw----  1 uucp  dialer  66, 7 May 19  2021 /dev/ttyU7

To create the nabu group and user on NetBSD or Ubuntu Linux, you can use the following procedure:

% sudo groupadd nabu
% sudo useradd -d /nonexistent -s /sbin/nologin -g nabu -c "NABU User" nabu
% sudo usermod -G dialer nabu     # NetBSD
  -- or --
% sudo usermod -G dialout nabu    # Ubuntu

The procedure on other systems is left as an exercise for the reader.

If you plan to serve local files or use any of the storage extensions (either NHACP or RetroNet), then you will want to create select locations for this purpose and create the necessary directories. On my local NABU server, I have the following directory layout:

neo2-nas:thorpej 26$ pwd
/export/nabu
neo2-nas:thorpej 27$ ls -l 
channels/  storage/   
neo2-nas:thorpej 27$ pwd    
/export/nabu
neo2-nas:thorpej 28$ ls -l                                                     
total 8
4 drwxr-xr-x  6 thorpej  wheel  512 Feb 15 13:46 channels/
4 drwxr-xr-x  4 thorpej  wheel  512 Feb 15 13:48 storage/
neo2-nas:thorpej 29$ ls -l channels/                                           
total 24
8 drwxr-xr-x  2 thorpej  wheel  7168 Feb  4 10:17 cycle1/
8 drwxr-xr-x  2 thorpej  wheel  7168 Feb  4 10:21 cycle2/
4 drwxr-xr-x  2 thorpej  wheel   512 Feb 15 13:36 hacking/
4 drwxr-xr-x  2 thorpej  wheel   512 Feb 15 13:46 rn-hacking/
neo2-nas:thorpej 30$ pwd             
neo2-nas:thorpej 30$ ls -l storage/                                            
total 8
4 drwxrwxr-x  2 thorpej  nabu  512 Feb 15 13:48 living-room-nabu/
4 drwxrwxr-x  2 thorpej  nabu  512 Feb 15 13:48 mame-nabu/
neo2-nas:thorpej 31$ 

In this example, I have local copies of the original 1984 NABU Network cycles (that I slurped down from cloud.nabu.ca), plus a couple of additional local channels for my own hacking purposes. I've also configured locations for the NABU to access locally stored files using the storage extensions.

The next step is to set up your nabud configuration file in $(prefix)/etc/nabud.conf. nabud's configuration is held in a JSON-format file. You can start with the example configuration file provided here. Note that the example has a lot of things in it that you may not need. The configuration file is documented in the nabud(8) man page.

The next step is to install the appropriate start-up "extra" for your system. If you are interested in providing extras for your favorite operating system, please let me know!

A launchd plist file for nabud is provided in $(prefix)/share/nabud/launchd/nabud.plist. By default, it runs nabud as the "nabu" user and sets its umask to 002. Install it and start nabud like so:

% sudo cp $(prefix)/share/nabud/launchd/nabud.plist /Library/LaunchDaemons
% sudo launchctl load /Library/LaunchDaemons/nabud.plist

A start-up script and configuration file are provided in $(prefix)/share/nabud/rc.d/nabud and $(prefix)/share/nabud/rc.conf.d/nabud. By default, they run nabud as the "nabu" user and set its umask to 002. Install them and run it like so:

% sudo cp $(prefix)/share/nabud/rc.d/nabud /etc/rc.d
% sudo cp $(prefix)/share/nabud/rc.conf.d/nabud /etc/rc.conf.d
% sudo /etc/rc.d/nabud start

A start-up script is provided in $(prefix)/share/nabud/rc.d/nabud. You will need to edit your /etc/rc.conf.local file to specify the options to pass to nabud. The recommended settings are:

nabud_flags="-u nabu -U 002"

Next, edit your /etc/rc.conf file to add nabud to the "pkg_scripts" variable. Then copy the start-up script into place and run it:

% sudo cp $(prefix)/share/nabud/rc.d/nabud /etc/rc.d
% sudo /etc/rc.d/nabud start

A systemd service file is provided in $(prefix)/share/nabud/systemd/nabud.service. By default, it runs nabud as the "nabu" user and sets its umask to 002. Install it and run it like so:

% sudo cp $(prefix)/share/nabud/systemd/nabud.service /lib/systemd/system
% sudo systemctl daemon-reload
% sudo systemctl enable nabud.service
% sudo systemctl start nabud.service

A control program, nabuctl, is provided that allows you to interact with nabud to change channels, list connections, display channel listings, etc. nabuctl must be run on the same system where nabud is running.

Upon start-up, nabuctl does a handshake with the server to ensure they're the same version:

% nabuctl
Server version: 1.1
nabuctl> 

There is some basic help available:

nabuctl> ?
Available commands:
        exit
        quit
        help
        ?
        channel
        connection
        list
        show
nabuctl> 

You can list the channels available, as well as any current connections:

nabuctl> list channels
1  - NABU Network 1984 Cycle v1 (NabuRetroNet)
2  - NABU Network 1984 Cycle v2 (NabuRetroNet)
3  - DJs Playground Cycle       (NabuRetroNet)
9  - HomeBrew                   (NabuRetroNet)
11 - NABU Network 1984 Cycle v1 (Local)
12 - NABU Network 1984 Cycle v2 (Local)
19 - homebrew                   (Local)
nabuctl> list connections
1  - Serial   [1]  /dev/tty-uftdi-A10MHWD6-0
2  - Listener [1]  IPv6-5001
3  - Listener [1]  IPv4-5001
4  - Listener [2]  IPv6-5002
5  - Listener [2]  IPv4-5002
6  - Listener [3]  IPv6-5003
7  - Listener [3]  IPv4-5003
8  - Listener [9]  IPv6-5009
9  - Listener [9]  IPv4-5009
10 - Listener [11] IPv6-5011
11 - Listener [11] IPv4-5011
12 - Listener [12] IPv6-5012
13 - Listener [12] IPv4-5012
14 - Listener [19] IPv6-5019
15 - Listener [19] IPv4-5019
nabuctl> 

You can change channels:

nabuctl> connection 1 channel 9
/dev/tty-uftdi-A10MHWD6-0: Selecting channel 'HomeBrew' on NabuRetroNet.
nabuctl> 

Additional details for channels and connections can also be viewed:

nabuctl> show channel 9
Channel 9:
        Name: HomeBrew
      Source: NabuRetroNet
        Path: https://cloud.nabu.ca/HomeBrew/titles
        Type: NABU
 Listing URL: https://cloud.nabu.ca/HomeBrew/titles/filesv2.txt
    RetroNet: enabled
nabuctl> show connection 1
Connection 1:
         Name: /dev/tty-uftdi-A10MHWD6-0
         Type: Serial
        State: OK
      Channel: 9
 Storage area: /home/nabu/storage/living-room-nabu
     RetroNet: enabled
nabuctl> 

You can see the list of files available on a connections' channel, if that channel provides a listing:

nabuctl> connection 1 listing
=====> RetroNET
1  - CPM22.nabu                Cloud CP/M 2.2 (BIOS v3.5b)
2  - RetronetChat.nabu         Chat (v2.8b)
3  - Telnet Client.nabu        vt100 Telnet Client (1.0b)
4  - Slidesho.nabu             Slide Show Gallery
=====> Demos
5  - Demo - Christmas.nabu     Merry Christmas
6  - Demo - Bad Apple.nabu     Bad Apple!
7  - plasma.nabu               Plasma
8  - HelloNABUBounce.nabu      Hello NABU Bounce
9  - Mandelbrot.nabu           Mandelbrot
=====> Games
10 - brickbattle.nabu          Brick Battle (0.1b)
11 - gamemanyeah.nabu          Game Man Yeah! (0.8b)
12 - gamemanyeahprototype.nabu Game Man Yeah Prototype
13 - Nabutris.nabu             Nabutris
14 - doom.nabu                 DOOM!
15 - AQUATTACK.nabu            Aqua Attack
16 - FLIP_AND_FLOP.nabu        Flip and Flop
17 - GALAXIAN.nabu             Galaxian
18 - HEAVYWEIGHT_BOXING.nabu   Heavy Weight Boxing
19 - LASER_ATTACK.nabu         Laser Attack
20 - MANIA.nabu                Mania
21 - MINER2049ER.nabu          Miner 2049er
22 - MOONSWEEPER.nabu          Moon Sweeper
23 - MOTORCYCLE.nabu           Motorcycle
24 - MUMMYS_TOMB.nabu          Mummy's Tomb
25 - pac-man.nabu              Pac-Man
26 - Q-BERT.nabu               Q-Bert
27 - QUEST_FOR_TIRES.nabu      Quest For Tires
28 - TIME_PILOT.nabu           Time Pilot
29 - TRACK_FIELD_1.nabu        Track & Field 1
30 - UFOS.nabu                 UFOs
31 - WINGWAR.nabu              Wing War
=====> Utilities
32 - Remote FS Test.nabu       Remote File System Test
33 - ScanCodeViewer.nabu       Scan Code Viewer
34 - ScrollTest.nabu           Scroll Test
nabuctl> 

And you can select a file to loaded when the NABU boots and requests image 000001:

nabuctl> connection 1 file 13
/dev/tty-uftdi-A10MHWD6-0: Selecting file 'Nabutris.nabu'
nabuctl> 

• Fixed an error in the GET-STATUS,TRANSMIT response that caused problems with the newer alternate NABU development ROMs. Tip-of-the-hat to Nick Daniels for pointing it out.

• Experimental support for Cygwin (64-bit).
• Support command history / editing in nabuctl in Docker builds, plus some additional Docker fixes. From Christopher Masto.
• Added a FlowControl property to Connection objects. This allows users who have modified their NABU HCCA port to support RTS/CTS flow control to enable it.
• nabuctl now displays the serial connection properties (baud rate, stop bits, and flow control) when viewing connection details.
• nabuctl now displays the file that the NABU will receive as the default boot image (image 000001) even if this is not specified in the config file or selected with nabuctl. Suggested by jefferystone on Discord.

• Added command history to nabuctl on systems that have the BSD libedit library and on other systems that have a compatible library.
• Added a Baud configuration property to Connection objects. This allows users who have modified their NABU to use a different HCCA baud rate clock to specify the baud rate to use.
• Renamed the FileRoot property on Connection objects to StorageArea, as the old name could be confusing. The old name is still accepted for compatibility with existing configuration files.
• Changed nabud's -d flag to enable debugging on specific subsystems, reducing the amount of logs you have to sift through when trying to figure out a problem.
• Added "show all channels" and "show all connections" commands to nabuctl, which shows the details for all channels and connections, respectively, rather than just one at a time.
• Added a systemd extra for Linux, along with some other Linux-specific instructions, provided by sampson on Discord.
• Added Docker support, provided by Christopher Masto.

• Fix an issue reported by jefferystone on Discord -- if you selected a file on a "Listener" connection using nabuctl, it would not be properly inherited when the real TCP connection came in from an emulator.
• Fix some typos / spelling errors in the document you're reading now. Patch provided by cml37. Thanks!

• Tweaks to image cache management: images from local sources are cached less aggressively. This reduces the memory footprint of nabud at very little cost to overall performance, and also makes local NABU program development a bit easier as there is no need to manually clear the cache each time a new image is dropped into a local channel being used for that purpose.
• Added support for NabuRetroNet protocol extensions version v2023.02.03.00. This enables running the NabuRetroNet Cloud CP/M.
• Updated the example nabud.conf file to show storage and RetroNet options.

• Added support for the NABU HCCA Application Communication Protocol. This protocol is much better specified than the NabuRetroNet protocol (which doesn't even really have a specification) and is more easily extensible to provide other services besides storage (for example, network connection proxy, etc.). Information about NHACP can be found here.
• Added rc.d and rc.conf.d extras for FreeBSD.
• Added an rc.d extra for OpenBSD.
• Added a launchd plist extra for macOS.
• Another change for Linux's over-restrictive cfsetspeed(3). Thanks to tatokis for pointing it out and confirming the fix.
• Man pages for nabud(8) and nabuctl(1).

• Fixed a problem with Linux's overly-restrictive cfsetspeed(3) whereby attempting to set the native NABU baud rate would cause the entire serial port setup to fail rather then falling back to 115.2K baud.

• Added rc.d and rc.conf.d extras for NetBSD and a few other tweaks to make it ready for pkgsrc.
• Updated example config in preparation for additional NabuRetroNet channels.
• Fixed the time packet to properly report the day of the week.

• Experimental for the NabuRetroNet blob store extensions to the Adaptor protocol. These extensions allow programs running on the NABU to access up to 256 "slots" of cloud storage that are cached in the server. This opens up a lot of exciting opportunities for things like downloadable game levels, music tracks, etc. This work is currently unfinished, and is provided only as a preview.
• nabud now builds on Linux (built and tested on Ubuntu 22.04 LTS).
• Added -u user and -U umask options for easily running nabud as a minimally-privileged user.
• Added nabuctl, a program for sending control messages to nabud. This allows you to easily change the channel used by individual NABU connections, and list and select programs to run from the NabuRetroNet HomeBrew channel.

• Fix a compiler warning that was happening with some versions of Xcode on macOS.

• Support for remote sources, including NabuRetroNet, althrough NabuRetroNet's "HomeBrew" channel does not work due to how the data is vended by that channel.
• Support for SecureTransport on macOS, eliminating the dependency on OpenSSL on that platform.

• Added TCP connection support, for emulators such as MAME.
• Changed the build system to use GNU autotools.
• Several small bug fixes.

This was the initial "preview" release, just meant to get it out there for folks to play with. It supported only local sources and serial connections. Written over the course of a few days during the Christmas 2022 holiday break.

First off, I want to acknowledge the folks nominally responsible for this NABU "Great Awakening":

• Adrian Black and his Adrian's Digital Basement YouTube channel. I'm a Patreon patron of this channel and the early-access to Adrian's NABU video is how I first learned of these cool machines. I think it's fair to say that Adrian's video is what spurred the recent interest in these machines.
• DJ Sures (his YouTube channel here) who has some family history with the NABU and did a bunch of reverse engineering on the Adaptor protocol and has led the charge on the NABU RetroNet.
• Leo Binkowski (his YouTube channel here), a former NABU engineer who preserved a TON of stuff when the NABU company folded.
• The York University Computer Museum's NABU Network Reconstruction Project, which has been working with these machines for many years now, and has been super gracious even while being bombarded with requests for information.

I also want to acknowledge some people whose code I have borrowed or used as a reference for this project:

• Nick Daniels' NabuNetworkEmulator served as a reference for the NABU Adaptor protocol. The files nabu_proto.h and adaptor.c were partially derived from his work.
• David Kuder's nabu-tftp gateway for the Raspberry Pi Pico also served to clarify some bits of the Adaptor protocol.
• Alistair Crooks' "Minimal JSON" (libmj) was used to build the configuration file parser.
• The fetch library (libfetch) was written by primarily by Dag-Erling Smørgrav, with additional contributions by Joerg Sonnenberger and Thomas Klausner. The version here comes from The NetBSD Project.
• The NetBSD Project is where the file nbsd_queue.h comes from. <sys/queue.h> from BSD is one of the handiest system header files in existence and I wish it were available everywhere.