Chorded keyboard (a writing system for the blind) uses either 6 or 8 tactile 'points' from which all letters and numbers are formed. When Louis Braille invented it, it was produced with a needle holing successively all needed points in a cardboard sheet. In 1892, Frank Haven Hall, superintendent of the Illinois Institute for the Education of the Blind, created the Hall Braille Writer, which was like a typewriter with 6 keys, one for each dot in a braille cell. The Perkins Brailler, first manufactured in 1951, uses a 6-key chord keyboard (plus a spacebar) to produce braille output, and has been
Read-copy-update "RCU" was one of many contributions by the Linux community. Other names for similar techniques include "passive serialization" and "MP defer" by VM/XA programmers and "generations" by K42 and Tornado programmers. Techniques and mechanisms resembling RCU have been independently invented multiple times: Bauer, R.T., (June 2009), "Operational Verification of a Relativistic Program" PSU Tech Report TR-09-04 (http://www.pdx.edu/sites/www.pdx.edu.computer-science/files/tr0904.pdf) Read-copy-update In computer science, read-copy-update (RCU) is a synchronization mechanism based on mutual exclusion. It is used when performance of reads is crucial and is an example of space–time tradeoff, enabling fast operations at the cost of more space. Read-copy-update allows multiple threads