HP-42S
The HP-42S RPN Scientific is a programmable RPN Scientific hand held calculator introduced by Hewlett-Packard in 1988. It has advanced functions suitable for applications in mathematics, linear algebra, statistical analysis, computer science and... Wikipedia
Dimensions: 148×80×15 mm
Discontinued: 1995
Display size: 2 lines, 22 characters, 131×16 pixels
Entry mode: RPN
Firmware memory: 64 KB of ROM
Manufacturer: Hewlett-Packard