https://en.wikipedia.org/wiki/APL_(programming_language)#Hardware https://en.wikipedia.org/wiki/APL_(programming_language)#Har... you would add a special "type

https://en.wikipedia.org/wiki/APL_(programming_language)#Hardware https://en.wikipedia.org/wiki/APL_(programming_language)#Har... you would add a special "typeball" into your IBM Selectric Typewriter. Some pics: https://www.duxburysystems.org/downloads/library/texas/apple/cnthesis/selectric.htm https://www.duxburysystems.org/downloads/library/texas/apple... https://pierce.smugmug.com/Misc/APL-Typeball/i-pjq6hWC https://pierce.smugmug.com/Misc/APL-Typeball/i-pjq6hWC