BBC Micro

BeebEm - BBC Micro and Master 128 Emulator

BBC Micro


Help Contents

Download Software

BeebEm Website

Serial Port

In addition to connecting to the standard serial ports on the PC the serial port emulation in BeebEm has options to connect via TCP/IP to a local or remote IP address. You can use ROMs such as CommSoft or CommStar to connect to a Viewdata BBS, MUD server or any other type of server.

The serial IP features are selected via the IP destinations on the RS423 Comms menu. The "IP: localhost:25232" option is designed for use with the "tcpser" package, which emulates a modem. Download a prebuilt Windows binary (and RC11 sources) of The tcpser home is here.

Run the "go.bat" file to fire up an instance suitable for the localhost setting to talk to. This will also allow incoming connections, as that does all the answering business and passes the caller onto the Beeb via the pre-existing connection. This handles the handshake lines if you enable ip232 mode, so dropping RTS will drop an outward connection. Similarly DCD going up will be passed through to CTS.

Add the Commstar.rom to your ROM configuration (see "ROM Software" above) and start up BeebEm. On the Comms menu select the "IP: localhost:25232" and "RS432 On/Off". Type *COMMSTAR to start CommStar. In Commstar:

  • Press M to switch to mode 0
  • Press A to turn off Auto line feed
  • Press I and then R a few times to set the receive baud to 9600
  • Press C to enter chat mode

You should now be able send commands to the modem (tcpser), try typing "AT", you should get "OK" back. You can now "dial" into a server using the "ATD" command. Try connecting to the Ishar MUD server using "".

To make a direct connection to a server select the "IP: Custom destination" option. This requires you to manually edit the "IP232customip" and "IP232customport" parameters in the Preferences.cfg file and reload.

An additional option, "IP: IP232 mode", determines if the handshake lines are sent down the TCP/IP link or just generated locally from the presence of a valid connection.

A second additional option, "IP: RAW comms", disables special processing of charater 255 (used with tcpser, so leave RAW mode off when using tcpser).

If on startup, or when ticking the "RS423 On/Off" menu option, BeebEm cannot connect to the specified server, or if it loses connection subsequently, it will pop up a messagebox and disable RS423. Select the menu option again to try to re-connect and re-enable.

BeebEm will emulate the correct RX baud rate. This makes for a very realistic experience when talking at 1200 baud to a Viewdata host! TX is just sent out as fast as it will go.

Copyright © 2011 Mike Wyatt