System/360 was supposed to be ASCII from the get go, the architecture supports it (the RCA Spectra 70 series which was a System/360 architecture system was ASCI

System/360 was supposed to be ASCII from the get go, the architecture supports it (the RCA Spectra 70 series which was a System/360 architecture system was ASCII). All System/360 descendants support ASCII, the issue they ran into early in the System/360 program was accessories, IBM had lots of EBCDIC I/O devices, and developing a line of ASCII I/O devices would have delayed introduction of the line by a period of time.