RetroComputerInstructionManual

IMSAI8080esp

Using the IMSAI8080esp to access BBS systems

The IMSAI8080esp web interface and firmware includes support for accessing BBS systems over the internet. It does this by emulating an old-school AT compatible MODEM, bridging it to a TELNET connection, and displaying ANSI compatible text in the terminal.

Here’s how to log into a remote BBS.

  1. Make sure you are using the TTY: terminal, not the CRT:
  2. Boot a recent CP/M disk, and make sure KERMIT is available.
  3. A>KERMIT
  4. KERMIT>SET PORT UC1
  5. KERMIT>CONNECT
  6. KERMIT>ATD e.g. ATDBBS.ABYSSNODE.NET
  7. Click the “A” in the TTY: menu bar to switch to ANSI graphics
  8. The AT command to hangup is ATH

Who to call?

Try Telnet BBS Guide

AT Commands

In the olden days we used modems to dial up other computers. Modems were connected to serial ports, and controlled by sending specific commands - usually starting with “AT” and then another character or two. The IMSAI (and the VT132 card also from TheHighNibble) extends the AT set to include commands that will connect to a remote computer system over TELNET protocol. Here’s a list of commands.

AT COMMANDS:
AT  - 'AT' Test                 | A/  - (immediate) Repeat last
AT$ - Help                      | ATIn - Information 
ATZ - Reset modem               |
AT&F - Restore factory defaults | AT&W - Write settings to NVRAM
ATDhostname:port - Dial hostname, port optional (default:23)
+++ - Return to command mode    | ATO - Return Online
ATH - Hangup
AT&A - Enable Answer mode - listen for incoming calls
ATA - Answer
ATSn - Select register n
AT? - Query current register    | AT=r - Set current register to r
AT&K0 - Disable flow control    | AT&K1 - Enable RTS/CTS flow control
AT+W? - Query WiFi AP Join status
AT+W=ssid,password - Join WiFI AP
AT+W$ - Show WiFi IP adddress   | AT+W# - Show WiFi MAC adddress
AT+W+ - Reconnect WiFI AP       | AT+W- - Quit WiFi AP
AT+U? - Query OTA Update        | AT+U=url - Set custom URL for OTA update
AT+U^ - Upgrade to OTA Update   | AT+U! - Force Upgrade to OTA Update
AT+U$ - Show OTA Parition Status
AT+B? - Query Baud Rate         | AT+B=nnn - Set Baud Rate (4800..115200)
AT+T? - Query Telnet TERM       | AT+T=name - Set Telnet TERM