Simrad controls of that vintage connect to their course computers via SimNet - a proprietary variation similar to 0183. In your case, I'm assuming the computer is the AC20, but you need to check. The AC20 has inputs for other system components and interfaces with your networkable items, like a GPS or chartplotter. Some number of those will be NMEA, looks like 0183, but you need to find the manual for your computer and verify.