The HP 9865 is a digital cassette tape drive, used as an external tape drive with the HP 9830. (It was also used with other 9800-series HP machines.) A special plug-in I/O interface is used to connect a 9865 to the 9830.

The 9865 and the internal tape sub-system of the 9830 are functionally and electronically equivalent, they actually share 3 circuit boards, as well as the transport, in common. They both present the tape drive as a select-code device on the 9830 I/O bus.

The connector on the rear of the 9865 is a low-level, parallel, command-and-data interface to the drive. The plug-in I/O interface for the 9830 adapts this low-level interface to the 9830 I/O bus. In the 9830 internal tape sub-system, the equivalent circuitry is provided on board Assembly 61.

9865 I/O Adapter

An I/O adapter has been designed and constructed to interface the 9865 to a modern host. A control program running on the host is then able to exercise the 9865. This provides a means to capture and produce byte-level images of the contents of 9830 data cassettes. It makes possible the archiving of old tapes on modern media, and reproducing (duplicating) tapes from those images, irrespective of the file types or contents.

With an assembler and suitable file-formatting abilities it is also one means of getting binary programs into a 9830.

The 9865 I/O Adapter is constructed from 7 standard TTL ICs. As shown in the photos it can be constructed as a module which plugs into the connector on the rear of the 9865.

The link to the host is a simple clocked serial line, the same as that used with the MPSI.

Note the MPSI, while a lttle more complex to construct, provides equivalent capability using the internal 9830 tape drive, thus without requiring a 9865.