creat 1211
CTSS had a table of commands in A-core. Adding a command required rebuttembly of the supervisor. This was enough of a hbuttle that several extra commands were defined, named CTEST1, CTEST2, ... The first editor I ever used that let you change and input lines and then look at the resulting file was Art Samuel's CTEST9, in about 1963. I don't remember if the list was kept sorted and searched with binary search.
pale Sure there is. We did on the -10 from the time I was a newbie. If the command is not in the "shell" then a piece of user mode code will have...
The design of the proposed Multics shell inspired Noel Morris and me to build a "shell" for CTSS. One of the Multics features we copied was the ability to extend the command set arbitrarily, by searching directories for SAVED files. (This would have been early 1965.) Although this theoretically slowed down command issue by some amount, it was unmeasurably small and worth it for user convenience. Multics used hash tables for almost all lookups. In the early days everybody had a copy of a memo by Bill Poduska, "Notes on Searching and Sorting," and we applied the pattern wherever it applied. Nice thing about hash tables is that lookup doesn't slow down as the table grows.
In particular, a Multics directory was a structure containing header items and a PL-I area where the catalog entries were allocated. The directory had a hash table mapping names to entries. A command lookup involved a hash table probe for a few well-known directories on the user's search path.