HP 9865A

HP 9865A

HP 9865A - Summary

The Cassette Memory, model HP 9865A was introduced in 1972 as a modular cassette tape storage peripheral for the 9800 Series of desktop calculators. It had a dedicate interface oriented to HP 9810A and HP 9820A desktop calculators.

An introductory price was about USD 1700.

The HP 9865A cassette tape unit provides data and programs storage for the HP 9800 series desktop calculators. Data may be recalled from the cassette, modified and restored back in the same file. All files are sequentially numbered. The HP 9865A offers high speed search function to find a requested file on the tape regardless current tape position. A need for tape rewind in order to begin a searching is eliminated by software. Files are identified by a file number and other informations regarding how the files have been used. Checksums are used to verify programs and data. Re-reading is executed several time, if the file is not read correctly into calculator.
Several cassette tape units may be connected to a system and each is selectively addressed.
HP 9865A - assembly

This is a view to Mainboard fitted to bottom frame.

HP 9865A
This is a view to rear panel of the HP 9865A with power transformer, fuse holder and power line socket. Bottom is a plastic cover of interface connector.

HP 9865A
Main board on the frame is connected to the rear panel. The mainboard interface connector is inserted into plastic cover on the rear panel and the transformer is connected to the mainboard.

HP 9865A
To the rear panel is attached a metal holder for Regulator board and Filter board.

HP 9865A
Left and right sides of the HP 9865A frame are attached to the rear panel and bottom frame's part.

HP 9865A

Left and right board's holders are instaled into frame.

HP 9865A

The cassette tape unit door is mounted to the tape unit frame..

HP 9865A

The tape unit bracket is mounted to the tape unit. Whit this bracket, the unit is attached to the HP 9865A frame and to thie bracket is attached the Interconnect board.

HP 9865A

The Interconnect board is attached to the tape unit bracket with four screws and isolation pads - see Fig. 2 on this page.

Four small boards wired to tape unit need to be carrefully inserted into connection holes on Interconnect board.

HP 9865A
Fig. 1

HP 9865A

Fig. 2
The tape unit with door and Interconnected board is now inserted into HP 9865A frame and fixed with four screws.

HP 9865A

The front panel is inserted into cut outs at left and right frames, with two srews is fixed a top bracket and with other two screws the door bracket.

Into holes are inserted the Rewind switch (right top) and Power switch (left bottom). Two wires from the Rewind switch need to be connected to the pins on the Interconnect board (right bottom).

The Filter board and Regulator board are inserted into last two mainboard positions .

HP 9865A
All boards are inserted into HP 9865A.

HP 9865A
Bottom view to HP 9865A without bottom cover.

HP 9865A
Bottom view to HP 9865A with inserted bottom cover.

HP 9865A
Final step - right, left and top covers are fixed with screws to HP 9865A frame.

HP 9865A