Analogously, GDSes like SABRE still ran on mainframes until very recently (c. 2023) [0]. SABRE was written in some combination of assembly and some kind of in-h

Analogously, GDSes like SABRE still ran on mainframes until very recently (c. 2023) [0]. SABRE was written in some combination of assembly and some kind of in-house dialect of PL/I, if I recall. [0] https://www.theregister.com/2022/04/11/gds_gets_over_historic_formatting/ https://www.theregister.com/2022/04/11/gds_gets_over_histori...