Level 9 devised their own [[Interpreted language|interpretationinterpreted language]], A-code, around 1979. It was very memory efficient, mainly due to the advanced text [[lossless data compression|compression]] routines which could compress texts to about 50%.<ref name=nowgamer>{{cite web | url=http://www.nowgamer.com/company-profile-level-9/ | title=Company Profile: Level 9 | date=2008-12-16 | accessdate=2015-06-08 | url-status=live | archiveurl=https://web.archive.org/web/20160304195140/http://www.nowgamer.com/company-profile-level-9/ | archivedate=2016-03-04 }}</ref> The game data, which was identical for all platforms, was incorporated into the executable file for specific machines, together with the interpreter part. A-code underwent a few revisions: there are three distinct versions in all, plus several extensions which form new A-code versions of their own.
(Level 9 A-code should not be confused with the A-code language developed by Dave Platt in 1979 for the purpose of writing the highly popular [[Colossal Cave Adventure#Later versions|550 points extension]] of the original Adventure game.)
