Whoever said that the two chips installed in the radio only send a TTL signal to the DIN jack was correct. One of the chips is a Ne4040, the other, I think, is an 8281. If you are looking for that chip set, you can confirm those numbers with numerous TS440 modification sites. If someone is looking for them, I have a spare set of them somewhere, since I bought multiple sets from Jameco in the early 90's rather than buy one from Kenwood at double the price plus shipping. To use the TS440 with a computer, you will also need the TTL to RS232 interface from Kenwood that was mentioned earlier, or you will need to find an alternative circuit. I think I remember seeing one specifically for the 440 a long time ago in QST, but I may be mistaken. Mike Duke, K5XU American Council of Blind Radio Amateurs