CRT:ADDS 4000

The ADDS 4000 series is a series of text-only terminals with a monochrome screen that came in page-white, amber, or green colors. Named after the manufacturer "Applied Digital Data Systems" (later renamed to Boundless Technologies), they are compatible with PC101/102/106/107 or ANSI VT-220 keyboards via RJ11 connector on the left side.

Supported Terminal Emulators
The ADDS 4000 series is capable of emulating various terminals depending on model listed below.

Connecting to Linux Machine
The easiest way to connect the terminal to a Linux machine — such as a Raspberry Pi — is to obtain a DB-25 male to DB-9 female null modem cable and a DB-9 male to USB adapter cable. You must get one labelled "null modem", as it is cross wired to be used without a modem.

Connect the cables to each other, one end to the terminal's EIA port (fastest), and the other to a USB port on your Linux host device.

Terminal Setup

 * 1) Press `Ctrl + Scroll Lock` (may be "PrLne" or "PrMsg" on your keyboard) to access Setup menu.
 * 2) Press F1 to enter Quick menu (if not already selected). Set the following:
 * `Host/Printer=EIA/None (enables EIA port to be connected to Linux host)`
 * 1) Press F2 to enter General menu. Set the following:
 * `Emulation=VT100`
 * `(and optional settings to turn down the bell noise and set a screen saver to protect the CRT)`
 * 1) Press F3 to enter Display menu. Set the following:
 * `Display Cursor=On`
 * `Page Length=24`
 * `Screen Length=26`
 * `Columns=80`
 * 1) Press F4 to enter Keyboard menu. Set the following:
 * `Key Mode=ASCII`
 * 1) Press F6 to enter Ports menu. Set the following:
 * `EIA Baud Rate=115200 (if not available, note the value you choose)`
 * `EIA Xmt=Xon-Xoff`
 * `EIA Data Format=8/1/N`
 * `EIA Recv=Xany-Xoff(XPC)`
 * `EIA Parity Check=Off`
 * `EIA Xmt Pace=Baud`
 * 1) Press F7 to enter Host menu. Set the following:
 * `Comm Mode=Full Duplex`
 * 1) Press F9 to enter Emulation menu. Set the following:
 * `ANSI-ID=VT100 (this will identify the terminal as a VT100 terminal to Linux)`
 * `Status Line=Off (recommended to prevent burn-in with line/text at top of screen)`
 * 1) Press F13 (may be "Print" or "Print Screen" on your keyboard) to enter Exec menu.
 * 2) * Press Enter on "Save Terminal" and wait for "DONE" message.
 * 3) * Press Enter on "Save Session" and wait for "DONE" message.
 * 4) Press F14 (may be "Hold", "Break", or "Pause" on your keyboard) and Y to save and exit.

Linux Setup

 * 1) Enable the terminal console to be accessible by serial.
 * 2) * On a Raspberry Pi, this can be set by running `sudo raspi-config` and enabling the "Serial Port" option under Interface Options; or by running `sudo vi /boot/config.txt` and adding an `[all]` section at the bottom followed by `enable_uart=1`.
 * 3) Enable the USB serial port and set the baud rate to match the one you had set in the previous section.
 * 4) * On a Raspberry Pi, you can do this by entering the commands:
 * `sudo stty -F /dev/ttyUSB0 115200`
 * `sudo systemctl enable serial-getty@ttyUSB0.service`
 * `sudo systemctl start serial-getty@ttyUSB0.service`
 * 1) If a login prompt isn't shown on the physical terminal, reboot the physical terminal followed by the Linux machine and it should prompt you for a login on the physical terminal.