mc - Modemcap editor


mc [ modemcap ]


Using a full-screen display, mc is used to create or edit modem capability (modemcap) files. These files include settings and commands that control external modems for use with ProLine.

When mc is invoked without an argument, it reads the system configuration file ($/etc/rsrc/startup.rsrc) and loads the currently active modemcap file. Use cursor keys (or the T-pattern from the 8, 4, 5, and 6 keys on a numeric keypad) to move from field to field on the display. A “>” points to the current field.

A row of “buttons” at the bottom of the display controls file management functions:

[ Quit ]

Quits mc.

[ New ]

Work with a new modemcap file. This prompts you for a modemcap name. If the name given already exists, it is loaded into the editor. If the file you enter does not exist, a new modemcap is created.

[ Save ]

Saves changes made to the modemcap. You’re given the opportunity to save it under a different file name.

[ More ]

(Same as pressing the Tab key). Switches to the alternate modemcap editing screen. The primary screen includes communications settings and timing information. The secondary screen displays modem commands.

To activate a button, press the first letter of its name (e.g., “Q” to quit).

Communication Settings

To change items on the primary screen, use the right and left arrow keys, or 4 and 6 on the numeric keypad. The primary screen items are:

Variable Speed

Determines if the serial port rate should match the modem’s reported connection rate. Set to Yes for an old-style modem (typically, 2400 bps or slower). Set to No for high-speed modems that operate best at a fixed speed to employ features such as data compression.

High Speed

The highest speed both the modem and computer will accept.

Flow Control

Normally set to RTS/CTS if a hardware handshaking cable is used, otherwise, set to None.

Has Carrier Detect

Must be set to Yes for correct BBS operation.

Error Correction

Set to Yes if the modem includes commands to regulate error correction.

ATA Answers

Set to Yes unless using an old modem, such as the Apple Modem 300 or USRobotics Password, which cannot answer a ringing line with the ATA command.

Use DTR To Hangup

If the modem is used on an Apple IIGS with a cable that supports hardware handshaking, set this to No. Normally, this item should be set to Yes.


Hangup Duration

The time that DTR is held low to force a disconnect (used only if the previous item is set to Yes).

Result Code Delay

The time that the system waits for a response from the modem after sending a command.

+++ Guard Time

The delay before and after the modem escape command is sent.

Attention Delay

The delay before a new command is sent after receiving a response from a previous command.


Items on the secondary screen are:

Main Init

Commands that correctly configure the modem to operate with ProLine. This command normally starts out by setting the factory defaults (&F) and any other commands needed to adjust the defaults follow. ProLine does not require command mode echo, so E0 can be given.

Aux Init

Commands, such as S register definitions to further configure the modem for operation with ProLine. Most factory defaults are fine, except for S7, which should be set to 255 to allow ProLine to control the duration of connection attempts.

Exit Init

The command sent to the modem when the system shuts down.


The MNP On and Off commands adjust the modem’s error correction feature.


The Make Busy and Not Busy commands control the modem’s “hook” state. Make Busy takes the phone off hook. Not Busy puts the phone back on hook.


Hangup and Post Hangup commands are sent before and after, respectively, a disconnection request.


modemcap files

See Also