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Serial & Parallel Connections

GSSquared treats each serial or parallel port as a jack you can plug a virtual device into — the same idea as mounting a disk image on a drive.

What you can attach

Attachment Serial ports (IIgs SCC, Super Serial) Parallel card
None Port idle Port idle
File Capture TX data to a host file Capture printer bytes to a host file
Clipboard Capture TX to the host clipboard Capture printer bytes to the host clipboard
Modem Virtual Hayes modem (TCP dial-out) —
Serial Real host UART (macOS /dev/cu.*, skipping Bluetooth/debug/wlan system callouts; Windows COMn, skipping Bluetooth modem mappings; Linux /dev/ttyUSB* /dev/ttyACM* /dev/ttyAMA*, skipping Bluetooth/debug) —

When a File attachment closes, a short on-screen message shows the filename. When a Clipboard attachment closes (idle ~10s, or Ctrl-Reset on parallel), high-bit-stripped text is copied to the host clipboard and a toast reports the byte count. Newlines are normalized to LF; IIgs “Add LF after CR” CRLF pairs become a single line break.

Control Panel (while the machine is running)

  1. Press F4 (or click the Control Panel tab).
  2. Find the Serial / Parallel buttons (between the slot list and the drive icons).
  3. Click a port button.
  4. Pick None, File, Clipboard, Modem, or a host serial port listed by name (Modem and host ports only on serial jacks). The host-port list is rescanned every 2 seconds while the control panel or config editor is open, so plugging or unplugging a USB serial dongle updates the picker.

On Apple IIgs machines you will see the built-in ports (often labeled like printer/modem). Slot cards such as Super Serial or Parallel appear as their own buttons.

Config editor (saved with the machine)

When creating or editing a .gs2 config:

  1. Add the card (or use a IIgs platform for built-in serial).
  2. Use the Serial / Parallel row in the editor — click a port, choose the attachment.
  3. Save. Those choices become [[connections]] entries in the file.

In a .gs2 file

IIgs built-in SCC (no slot):

[[connections]]
port = "a"
device = "file"

[[connections]]
port = "b"
device = "modem"

Slot card (Super Serial or Parallel):

[[connections]]
slot = 2
device = "modem"

Optional path sets the capture filename for device = "file". For device = "serial", path is the host port name stored as written (/dev/cu.usbserial-…, cu.usbserial-…, COM3, /dev/ttyUSB0, …) — it is not resolved relative to the config file.

[[connections]]
slot = 2
device = "serial"
path = "cu.usbserial-A50285BI"   # macOS; on Windows use path = "COM3"; on Linux, /dev/ttyUSB0

Guest software programs baud / data / parity / stop bits on the SCC or 6551; those settings are passed through to the host port. If the dongle is unplugged, the emulator keeps the attachment and retries. On Linux, /dev/ttyUSB* is owned by group dialout (some distros use uucp); the local user must be in that group and re-login before GSSquared can open the port.

If you omit [[connections]], GSSquared applies sensible defaults (IIgs: file on one port and modem on the other on native builds; SSC → modem; parallel → file).