HP 9815A - Introduction
The desktop calculator HP 9815A was introduced in 1975 as the first of the third-generation desktop calculators.
It uses a 16-digit plasma display (gas-discharge display) made by Panaplex and a commercial microprocessor, a
Motorola type MC6800 with internal paralel bus.
The calculator has a thermal printer and a tape cartridge for data storage. In contrary on its predecessors
first generation desktop calculator (HP 9100A/B) and second generation (HP 9810A and HP 9820A), the HP 9815A
stores programs and data on magnetic tape cartridge known as DC100 or HP200.
Each DC-100 mini-cartridge has capacity of 94K bytes and was much smaller, lighter, and cheaper than the
first- and second-generation of HP desktop calculators.
For programming, the HP 9815A uses RPN (Reverse Polish Notation) system used on the handheld calculators with
a four level stack with all results in the x register. The calculator has 472 program steps optionally expandable to 2008 steps.
Price in year 1975 was US$2900.