Joe's HP 9815 Computer Page

Revised 10/19/2000

This Page Under Construction

A Transition, the HP 9815

HP 9815

The HP 9815 was introduced in the 1976 HP catalog. The 9815 was based on a Motorla 6800 CPU and was the first HP desktop to use a parallel bus internally. All of the machines after the 9815 used the parallel bus. It has many new features including an autostart capability, a ten key numeric keyboard, 15 special function keys, a 16 character LED display and a newly redesigned 16 character printer thermal printer. The tape drive was also a new design and could store 96k bytes on a HP 200 tape cartridge. Two I/O channels were optional. It was initially offered with 10 data registers and 472 programming steps and was upgradeable to 2008 steps. The 9815 used RPN logic and had 28 built-in scientific functions. HP introduced the 9815S in 1980. The 9815S replaced the 9815A option 001 and included the two I/O slots and 3800 programming steps as standard. HP dropped the 9815A from the catalog in 1981. The 9815S was dropped after the 1982 catalog. The HP 9815 was HP's smallest desktop calculator. The one in this 9815 picture is missing it's cover over the paper roll.

9815 Options
Option 001 (9815A only) 2008 programming steps
Option 002 (9815A only) two I/O slots

Price (1976) 9815A $ 2,900
(1977) 9815A $ 2,900
(1979) 9815A $ 2,900
(1977) 9815S $ 3,950
(1981) 9815S $ 3,800

Size and Weight: Base 14 x 14x 4 inches 14 pounds

9815 interfaces
HP 98130A is used for the 9872 plotter.
HP 98131A is used for the 9871 impact character printer.
HP 98132A picture is used for the 9862 plotter
HP 98133A picture is used for 9 digit BCD input and 8 bit parallel output.
HP 98134A is used for bi-directional 8 bit parallel I/O and can be used to connect the 9815 to other systems.
HP 98135A is used to connect up to 14 HP-IB devices and has no interrupt capability.
HP 98136A is used for RS-232 or current loop serial communications.

Shameless Plug, I need a standard HP 9815, HP 9815Ss with the other interfaces and manuals for these machines. I have not been able to find out how data was written to and read from the interfaces. I would also like to have software for these machines. The only software that I have is for a plotter demo for a plotter that I don't have! If you have anything for these computers, send me a message.

This page was created by Joe Rigdon, Oviedo, Florida in the interest of preserving HP calculator and computer technology and history. All original material is copyright 1997 by Joe Rigdon, all rights reserved. Please send comments to