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January 31, 2023

IMSAI8080 replica connecting to a Linux machine via acoustic coupler

IMSAI8080 replica connecting to a Linux machine via acoustic coupler. Setup:

IMSAI replica running CPM/2.2. By default the machine sets UC1 port as the virtual AT modem. Acoustic coupler was connected to IMSAI serial port, so I needed to execute the script "porta" to point UC1 to the physical port.

Acoustic coupler: 300bps, caller only, connected to the IMSAI serial port

Old pulse (yep, pulse) dialing phone (Heraldo by CITESA) connected to the ATA.

Gandstream HT802 ATA. This ATA provides some interesting features, like inter-port dialing (so I can call from one port to another without any external PBX like Asterisk), and automatic pulse to DTMF conversion.

Old SupraExpress 336 modem connected to the ATA with phone cable, and to an old laptop via RS232 to USB cable.

Old laptop running mgetty

The steps in the video are:

Turn on IMSAI replica

telnet to the IMSAI and execute porta script. Execute kermit, setting uc1 as the port (the RS232 physical one) and connecting to it

Call to the Linux computer using the phone connected to the acoustic coupler

The terminal on the left is tailing the mgetty log

Connection to the Linux host is established

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