COURYHOUSE at aol.com wrote: It is a Bell 103A compatible modem (110 or 300 baud) used with the NCR 260 series of thermal printing terminals. The 260 came in several variants: -1 (receive only), -2 (keyboard send/receive), -6 (Automatic (cassette tape) send/receive). I worked with them at NCR in 1973 and 74. I still have the manuals, and just a few days ago scanned them for Bitsavers. If you need a copy I can send you the raw TIFF files (one per page). Both the -400 and -500 were EIA I/O to the terminal. The C260-400 connected to a Bell System DAA (Data Access Arrangement), while the C260-500 was an acoustic coupler. The acoustic coupler had a solenoid that would would automatically raise and lower the handset on the telephone! Back in those days you could not connect anything directly to the telephone lines -- you had to use the telco-supplied DAA (kaching!) or an acoustic coupler. I don't know if this modem can be connected directly to a phone line without a DAA. I think the asking price is totally unrealistic unless you are a rabid collector of NCR gear. Alan Frisbie