FYI, the IBM S/360 did support ASCII[0]. A bit in the program status word indicated if the machine was running in ASCII or EBCDIC mode. Most customers ran EBC

FYI, the IBM S/360 did support ASCII[0]. A bit in the program status word indicated if the machine was running in ASCII or EBCDIC mode. Most customers ran EBCDIC because it was more compatible with their masses of punch card originated data (no translation required). For the S/370, for virtual memory, a bit in the program status word was needed to indicate addresses were real or virtual. IBM surveyed its customers and found almost no one was using ASCII so its bit was taken for virtual memory. [0] Page 70 of http://bitsavers.org/pdf/ibm/360/princOps/A22-6821-0_360PrincOps.pdf http://bitsavers.org/pdf/ibm/360/princOps/A22-6821-0_360Prin...