HP introduced the 80 Series in 1979, beginning with the 85. The 80 Series was developed in Corvallis, Oregon, which at the end of the 1970s had the charter for all HP calculator products. The machines in the 80 Series were the first desktop computers produced in Corvallis. The 80 Series was HP's first truly low-end technical computer range. The 85 cost less than half the price of the 9825. Like the 98X5 computers and their predecessors, the 80 Series employed pluggable ROM modules to add product capability (I/O connections, language enhancements, etc). Subsequent computers from HP would have these enhancements either built-in or handled by software. All 80 Series computers came standard with ROM-based BASIC, and only the 9915 had a cooling fan.
These products (excluding the 9915) were developed and manufactured at HP's Corvallis Division.
Be sure to visit Olivier De Smet's site to try his Series 80 emulators.
John Shadbolt also has a terrific site with useful information on 80 Series computers: 1980s Vintage Computers.
Click here to visit Larry Atherton's HP-85 refurbishment site. Larry completely rebuilds HP-85 computers , replacing the tape drive with a reliable QIC drive.