https://en.wikipedia.org/wiki/IBM_2741

https://upload.wikimedia.org/wikipedia/commons/2/23/IBM_2741_%28I197205%29.png
By nn - Informatyka, rok 1972, Public Domain, https://commons.wikimedia.org/w/index.php?curid=25787907


https://upload.wikimedia.org/wikipedia/commons/d/d6/IBM_2741_Communications_Terminal.jpg
IBM 2741 terminal with APL keyboard
By Oscar.nierstrasz - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=41093026

https://upload.wikimedia.org/wikipedia/commons/9/9f/APL-keybd2.svg
APL keyboard
By User:Rursus - APL-keybd.svg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2456412