Hayes modem emulation

Copperline can put an emulated Hayes-compatible AT command modem on the Amiga’s serial port. The modem carries serial traffic over TCP, so terminal programs (such as Term, NComm, or JR-Comm) and BBS software can dial Internet telnet BBSes or accept incoming connections.

The command interpreter supports the standard Hayes AT commands (ATD, ATA, ATH, ATO, ATE, ATQ, ATV, ATI, ATZ, AT&F, AT&C, AT&D, AT&W, S-registers, and the +++ escape) and the AT* extension set of the WiModem232.

Configuration¶

In the launcher:

1. Navigate to I/O Ports -> Serial Port.

2. Set Device / Mode to Modem.

3. Optionally set a Listen address (for incoming calls) and the Telnet NVT translation toggle.

In copperline.toml:

[serial]
mode = "modem"
# listen = "0.0.0.0:2323"   # Bind port for incoming calls (optional)
# telnet = true             # Enable Telnet NVT translation at power-on

From the command line:

copperline --model A1200 --serial modem KICK31.ROM

Dialing outbound connections¶

In your Amiga terminal software, use standard AT dialing commands:

• ATD<hostname>:<port> or ATDT<hostname>:<port> (ATDP also works): Connects to a TCP endpoint (for example ATDTbbs.example.com:23). Without a port, the modem’s default port is used: 23 (telnet) unless AT*P changed it.

• ATD<number>: A target of digits (plus # and *, with -, spaces, and parentheses ignored) is looked up in the [serial.phonebook] table; a number that is not there gets NO CARRIER. An entry without a port uses the default port:

[serial.phonebook]
"5551234" = "bbs.example.com:23"
"5555678" = "bbs2.example.com"

Result codes returned by the modem:

• CONNECT [baud]: The TCP connection is established. The rate shown is the one set with AT*B, or else the guest’s serial port rate.

• BUSY: The target refused the connection.

• NO CARRIER: The connection failed or was dropped.

• OK and ERROR, as usual. ATV0 switches to numeric codes and ATQ1 silences them.

Dialing out resolves the host name and connects on the emulation thread (with a five-second connect timeout), so emulation pauses briefly while the connection is made.

Handling incoming calls¶

To allow inbound connections, specify a listening address with listen = "0.0.0.0:2323" (or via the launcher). Without one, or a port stored with AT&W, the modem only dials out.

• When a remote host connects, the modem sends RING to the guest every four seconds.

• Answer manually by sending ATA, or configure auto-answer using register S0 (for example ATS0=1 answers on the first ring).

• If an incoming call is not answered within 10 rings, it is disconnected.

• A second caller who connects while a call is active or still ringing gets a busy line: the connection is accepted and closed at once.

Telnet NVT translation (AT*T1 / AT*T0)¶

By default the modem passes the raw 8-bit byte stream. For telnet servers that expect RFC 854 option negotiation:

• AT*T1 (or telnet = true in configuration): Enables telnet NVT negotiation for the next call. The modem accepts ECHO, SUPPRESS-GO-AHEAD, and BINARY, answers TERMINAL-TYPE with ANSI, NAWS with a window size, and SEND-LOCATION with Copperline, and refuses every other option. It also handles IAC (0xFF) escaping.

• AT*T0 (default): Raw 8-bit binary transport. Use this mode for BBS systems transferring binary files with ZModem, XModem, or raw protocols.

WiModem232 command extensions¶

AT&W saves the current settings, including an AT*L port, and ATZ reloads them; AT&F restores the factory defaults. The stored profile is modem.profile in the NVRAM folder ([paths] nvram). Keys set explicitly in [serial] take precedence over the stored profile at power-on, and --factory neither reads nor writes it.

S-registers¶

Other S-registers read as 0 and ignore writes.

RS-232 control lines¶

• DTR (AT&D): Under AT&D2 (default) and AT&D3, dropping DTR (for example by closing the terminal software or resetting the serial port) hangs up the active call. AT&D0 and AT&D1 are accepted but not modelled.

• DCD (AT&C): Carrier Detect follows the call: it is asserted while a connection is up (including after a +++ escape to command mode) and drops when the call ends. AT&C0 forces DCD permanently high.

• CTS / DSR: Permanently asserted. RTS is accepted but there is no hardware flow control.

• RI: There is no Ring Indicator line; incoming calls are announced by the RING result code.

Scripted session replay¶

For deterministic automated testing, CI, or demo playback, a scripted session file can stand in for the network, so a headless run that dials out is reproducible byte for byte:

[serial]
mode = "modem"
session = "session.txt"

--serial-session FILE does the same from the command line (and implies --serial modem). A scripted session only dials out, so it cannot be combined with listen. Rewinding or loading an earlier save state restarts the script from the top.

Directives in a session file, one per line (blank lines and lines starting with # are ignored):

# Session script example
accept
delay 0.5
send \r\nWelcome to the BBS\r\n
expect BYE\r
send \r\nGoodbye\r\n
close

Each accept or refuse covers one call. A dial with none queued gets NO CARRIER, and a script that runs out mid-call leaves the line up with nothing more arriving.