The Computer HP Wouldn’t Let Steve Wozniak Build


In the mid-1970’s Steve Wozniak was designing his own hobbyist computer that would become Apple’s first model, the Apple I. He was working at Hewlett-Packard and offered HP the rights to his design. His managers at HP turned down his offer, and Steve eventually ended up leaving HP to join Steve Jobs and help launch Apple Computer.

HP’s refusal might have been based, in part, on a lack of interest due to a competing product they were developing internally, called “Capricorn”, that would later become the HP 80- series of personal computers, starting with the HP-85. As told by the excellent book “Fire in the Valley”, a small group of engineers at HP in Cupertino, California, began designing a new personal computer as an extension of HP’s existing calculator line. As this project was getting started, it was moved to HP’s facility in Corvallis, Oregon. While many engineers at HP were reluctant to move to Corvallis, Steve Wozniak very much wanted to be part of the team designing this computer and might have joined the HP Corvallis team. But this was not to pass: later that year, in October, after HP had turned Steve Wozniak away from Project Capricorn, Mike Markula made his famous visit to Steve Job’s parent’s garage to see the new Apple I computer.

In the early 80’s, while a student at Crescent Valley High School in Corvallis, I joined HP’s Explorer program for students, where we’d spend time after school with HP engineers at the Corvallis campus. The first IMG_1933personal computer I got to use was the new HP-85.

Out of a sense of nostalgia I bought this HP-85 in great condition on eBay.

While the HP-85 had some innovative features, such as the built-in CRT display, thermal printer, tape drive for program storage and expansion slots, the specifications were not necessarily ahead of the market at the product’s introduction in 1980. With an initial price of $3,250, only 8 K of memory, a small display (32 columns x 16 rows of text — not exactly a “retina” display!) and limited storage (217 kilobytes per tape cartridge using the built-in drive), the HP-85 fell behind the state-of-the-art into the 80’s.

The HP-85 was manufactured at the HP Corvallis, Oregon campus; it was fun to walk into the facility and see these computers and HP’s calculators (HP’s Ink Jet printers hadn’t been invented yet) being made. The machines were assembled by hand and, if you look closely at the picture below, you’ll see the workers’ initials where they signed off their assembly step. There are also signatures on the inside of the case. The quality is amazing: this little PC still runs after almost 40 years!

IMG_1907So having gone through the trouble of finding this old computer, what can you do with it? Not much, other than write your own programs or run existing software. There’s no hardware or software support for modern networking protocols. The tape drive no longer works, as the rubber capstan wheel has deteriorated. While this can be relatively easily repaired, there are actually much better solutions for loading and running programs on the computer.

One solution, called “HPDrive” (available here), developed by Ansgar Kueckes, emulates a variety of HP-85 compatible floppy disk drives in software on a host PC. This is the approach I took, running the HPDrive emulator on a Windows 10 PC. I’m still amazed that two computers, separated by almost 40 years of progress, can still communicate!  This miracle of technology is made possible by HP’s long-running support for their own HP Interface Bus (HP-IP) protocol, used originally to connect measuring and scientific equipment to other devices. HP chose this protocol for external expansion in their first personal computer.


The link above has the details, but basically you install (after finding one on eBay!) an HP 82937A HI-IB interface cartridge in one of the HP-85’s open expansion slots (along with a ROM drawer cartridge populated with the 16K memory expansion and Mass Storage ROMs), a compatible HP-IB card in your PC (I’m used a National Instruments 488.2 PCI interface card, also found on eBay). Running the HPDrive program on the host PC makes that computer appear to the HP-85 as a connected floppy drive. You “point” the HPDrive software to an existing .hpi file, which stores the contents of a floppy disk; typically containing either a number of freely available application packs for the HP-80 series of computers, or any software you write yourself, in BASIC. For those interested, the gory details of how this all works is documented on this page of Ansgar’s web site.


So what is using an almost 40-year-old PC like? If you’re with me this far, I made s short demo video of three Application Pack programs: an adaptation of the classic ’70’s “Star Trek” game, written by Mike Mayfield and friends in 1971 on a mainframe computer at UC Irvine, a golfing game to show that yes, graphics were possible — sort of — on the HP-85 and finally, an “amortization” program for doing time-value-of-money calculations. This all looks quaint today, but you have to think back to the 70’s, when this was still novel stuff.