Click here to download the HP-85 EMULATOR 2.0
last updated June 1, 2006
(Download size approximately 1.9 Mbytes)

This is a hobby project of mine, and has very little to do with my puzzle games (although the Games Pac II included some of my earliest arcade games). See the "HISTORY" section of the README.TXT file for more about my involvement with the HP-85.

The HP-85 was a computer designed by Hewlett-Packard in the late 1970's and was introduced in December 1979. This emulator is a Microsoft Windows 32-bit program that emulates the hardware of an HP-85, including the CPU, RAM, ROM, keyboard, CRT, beeper, internal thermal printer, tape cartridges, two diskette drives, and an external printer. There is no support for the back-plane I/O ports, except for the access to the diskette drives and the external printer. The actual bytes from the system and plug-in ROMs are used and "executed". The displayed output will give you a very close approximation of a real HP-85 computer.

NOTE: This is the first public release, and as such does not have very extensive documentation or instructions. Please read the README.TXT file in the installed directory, as it has some valuable information (this is the file that's is shown when you click on HELP, but it's much easier to read in a separate text editor). The download includes two tape cartridges, the HP-85 Games Pac and the Assembler ROM tape. Once you download and install the emulator (just download and run the file above to install it, which will unZIP itself into c:\hp85 unless you change that), then run the HP85.EXE program from the installed directory. The emulator can be drawn at "normal" size or "double" size (double pretty much requires that your display be running at 1280-pixel horizontal resolution or higher, otherwise you'll want to stick to "normal" size (see the "EMULATOR OPTIONS" menu).

The emulator includes a disassembler and debugger that lets you examine the HP-85 ROM code, single-step through it, set breakpoints, etc.

TAPES: to load a tape cartridge, just click on the tape drive door (above the "CRT"), and a dialog will open showing the available cartridges. In the TAPES dialog, you can also create "new" tapes by clicking on the NEW pushbutton and entering a new name. Before you can use the new tape, you will need to do an ERASETAPE command on the HP-85. If you try to access the blank tape BEFORE doing an ERASETAPE, the tape will search and search and search and very likely end up off the end of the tape. I believe this to be a bug in the tape emulation code, and I plan to investigate and fix it. The TAPES dialog also lets you RENAME, DELETE, or toggle the Write-Protect switch on the currently selected tape. The status bar above the tape display will have a light-red background if the tape is write protected and a light-green background if not. If one tape is loaded, and you load another tape, the already loaded tape will be automatically ejected and the new tape loaded. The "tapes" are stored in individual files in the TAPES sub-directory. The status output above the tape cartridge (above the "CRT"), besides showing the write-protect status, also shows the two tracks of the tape and a moving indicator that shows where (and how) the HP-85 is currently accessing the tape. A blue '<' or '>' indicates hi-speed searching, a green ']' or '[' indicates lo-speed reading or searching, and a red ']' or '[' indicates lo-speed writing.

DISKS: these are handled much like the tapes. Click on the left or right diskette drive latch, and a dialog will appear. The "disks" are stored in a DISKS sub-directory. When you write-protect a diskette in this dialog, it does NOT make the file in the DISKS sub-directory write-protected, but rather sets a byte (at offset 255 in the file, the last byte of the "volume" sector) to 0 or 1, and that value is used by the emulator to control the write-protected status of the diskette.

If you have any questions, problems, suggestions, etc. regarding this emulator, please feel to contact me.


The HP-85 Emulator distribution (above) includes many HP-85 Application Pacs, including the Games Pac and the Games Pac II. However, for those of you with a REAL HP-85 who might like to get the Games Pac II (or Games Pac Misc) onto LIF diskettes and into your real HP-85, below are ZIP files of those Pacs. The files were saved using the LIFUTIL utility, with LFS headers on each file. The LIFUTIL is also available here, but BEWARE: it requires an older PC for it to run, as it won't run on most modern PCs.

LIFUTIL - self-extracting archive of the LIF->DOS and DOS->LIF file conversion utility (requires 3.5" or 5.25" diskette drive and an older PC).
HP-85 Games Pac II - ZIP file of all the files (in LIFUTIL format) from the 2nd HP-85 Games Pac (includes a JPG file containing the BasicExchange newsletter article describing the games).
HP-85 Games Pac Misc - ZIP file of miscellaneous HP-85 Games that were never officially distributed.


At the time of this writing, these other web sites exist that contain a great deal of information and files regarding the HP Series 80 computers, including ROM images, software, and manuals
for both the HP-85 and the HP-86/87:

Note: at this time (Nov 2008) seems to have disappeared.  Here are some of the files that were available from that site:
NOTE: The site seems to be back up, but I'll leave the downloads here for now anyway...

A completely different emulator for the Series 80 was written by Olivier De Smet. His emulator can be downloaded from:
or directly from here:
ZIP of source for Olivier De Smet's HP-85B/HP-87 Emulator
ZIP of Windows version of Olivier De Smet's HP-85B/HP-87 Emulator

I have no connection with any of these additional websites, so WYSIWYG ("what you see is what you get").


Around 1979, someone in Ft. Collins, Colorado had some metal "Capricorn" belt-buckles made for the HP-85 sales force (I think). (HP's internal code name for the HP-85 project was "Capricorn".) Bill Kemper, an HP-85 Applications Engineer, received some of these, and he gave me one of them. I still
have the buckle, which has zodiacal capricorn goat on the front, and on the back says, "(c) CAPRICORN HP-85 A/S * DESIGNED AND SCULPTURED BY: HAL PLATT * HEWLETT-PACKARD CO. FT. COLLINS CO. * NOGARIS ART FOUNDRY". I wore that belt buckle for 15-20 years, until I got tired
of wearing a belt... These are pictures of its front and back: