The ASCII feature of S/360 probably wasn't used because it's nearly useless. Turning on ASCII mode caused PACK & CVD to generate ASCII sign codes and UNPK to generate ASCII zone codes. As far as I can tell, that's it. I'd say that the much later PKA & UNPKA instructions make a lot more sense than a system option, so I suppose somebody thinks the function is useful. But you could always convert zoned decimal with NC/OC or, of course TR.
ED isn't in my very old S/360 PoOp (A22-6821-0), but ED certainly came out soon, long before the ASCII bit was officially dropped. Anyway, I don't know whether it supported ASCII mode or not. sas
