Curly braces: An evolution of UNIX and C
The article discusses the evolution of curly braces in UNIX and C programming. It highlights the challenges faced in early computing environments, particularly with the Teletype Model 33, which lacked certain characters. The introduction of trigraphs and digraphs in C allowed for the representation of these missing characters, showcasing the adaptability of programming languages over time.
- ▪The Teletype Model 33 could not produce lowercase letters or curly braces, which were essential for C syntax.
- ▪C89 introduced trigraphs to represent missing characters, while C95 later introduced digraphs for better readability.
- ▪UNIX V4 implemented character translation to allow the use of curly braces on terminals that could not produce them.
Opening excerpt (first ~120 words) tap to expand
Thalia Archibald's blog Curly braces: An evolution of UNIX and C 19 May 2026 How were { } curly braces typed with a Teletype Model 33 on UNIX? These characters are especially important for C, but absent on this terminal. I was just asked a similar question 1 and in response, this is a tour of the coevolution of UNIX and C, from this perspective, featuring “hello, world” through the ages. This work is entirely my own (no AI) and the code samples are my construction. Sources for all inferences are cited. ASCII 1963 The Teletype Model 33 famously couldn’t write lowercase letters. This teleprinter was designed around the first edition of the ASCII standard, ASA X3.4-1963, which hadn’t yet decided lowercase was worth adding.
…
Excerpt limited to ~120 words for fair-use compliance. The full article is at Thalia Archibald’s blog.
Discussion
0 commentsMore from Thalia Archibald’s blog
