Keystone is an American company that produced calculators in the 1970s. Keystone calculators are known for this use of Panaplex displays on portable calculators.
Media in category "Keystone"
The following 5 files are in this category, out of 5 total.
Keystone 395 board bottom.jpg 1,799 × 2,782; 2.11 MB
Keystone 395 board top.jpg 1,435 × 2,300; 1.03 MB
Keystone 395 keypad rear.jpg 1,600 × 1,998; 954 KB
Keystone 395 rear.jpg 1,777 × 2,712; 1.63 MB
Keystone 395.jpg 1,545 × 2,265; 713 KB
