[alwold]

It looks like EBCDIC supports lower case letters just fine. Any idea why they used all uppercase? I've noticed use of all uppercase on a lot of old systems, and always sort of wondered why. Is there a good technical reason? Maybe a data type that uses less space per letter?

[Someone]

EBCDIC has lowercase because it is _Extended_. http://en.m.wikipedia.org/wiki/BCD_(6-bit):

"BCD ("Binary-Coded Decimal"), also called alphanumeric BCD, alphameric BCD, BCD Interchange Code, or BCDIC, is a family of representations of numerals, uppercase Latin letters, and some special and control characters as six-bit character codes.

[...]

IBM later created the 8-bit code EBCDIC (Extended Binary-coded Decimal Interchange Code) based on BCD."

[ams6110]

Older line printers and early teletypes didn't have lower case.