1980s Vintage Computers

Hewlett-Packard Series 80 - HP-9915


The HP-9915 was designed as an industrial computer, for mounting in a rack to control test or production equipment. It was based on an HP-85, with the following changes:

  • Front panel control buttons and LEDs added (which required software in the form of the Program Development ROM).
  • Better self-fault diagnostic capabilities, provided by an additional microprocessor.
  • A cooling fan (no other Series 80 machine needed one). 
  • Built in EPROM board for user software (Basic and Binary programs).
  • No built-in printer option.
  • Optional video output to an external monitor (as per HP-86) and keyboard connector.
  • Optional tape drive.

The photo above shows a 9915B together with the plug-in keyboard. The 9915B was based on the 85B (so has an Electronic Disk and has 64K RAM), there was also a 9915A based on the 85A (thanks to vp for sending me one of these). The rear of the unit has three expansion slots which take the standard series 80 cards such as the HP-IB interface. 

Built in to the mainboard are six ROM sockets, so there is no need for a ROM Module. 


The 9915 was supplied with two ROMs, I/O and Program Development. The PD ROM adds additional commands to support the front panel LEDs, and to allow access to the EPROM board as a mass storage device.

EPROM board

Note that the tape drive, keyboard input and video output were all options.

Typically an application would be developed using the HP-85, then this would either be written to tape, or for demanding environments converted into EPROM format. HP produced a suite of utility programs to convert Basic and Binary programs to EPROM format, but currently these have yet to be found. I decided to try and work out a method, and with the help of the HP-9915 manuals available from the HP Computer Museum in Australia I succeeded. Here are my notes and program listings.

I would very much like to contact anyone with any of the 9915 specific software or any program listings, so please e-mail me.

HP Series 80 tips


This page was last revised on: 04/12/10