I'm fully conversant with UNPK, including the fact that the zone it sets depends on the value of the ASCII bit. How is that relevant to handling teletypes?
-- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 ________________________________________ From: IBM Mainframe Assembler List <[email protected]> on behalf of [email protected] <[email protected]> Sent: Sunday, August 9, 2020 10:53 AM To: [email protected] Subject: Re: Case Study: IBM SYSTEM/360-370 ARCHITECTURE (1987) On 2020-08-09 15:05, Seymour J Metz wrote: > How is the ASCII bit relevant to teletypes? It only affects the > handling of the sign nybble. You might want to check out the UNPK instruction. > Shmuel (Seymour J.) Metz > http://mason.gmu.edu/~smetz3 > > > ________________________________________ > From: IBM Mainframe Assembler List <[email protected]> > on behalf of Robin Vowels <[email protected]> > Sent: Saturday, August 8, 2020 11:40 PM > To: [email protected] > Subject: Re: Case Study: IBM SYSTEM/360-370 ARCHITECTURE (1987) > > ----- Original Message ----- > From: "Steve Smith" <[email protected]> > To: <[email protected]> > Sent: Sunday, August 09, 2020 10:57 AM > Subject: Re: Case Study: IBM SYSTEM/360-370 ARCHITECTURE (1987) > > >> The ASCII feature of S/360 probably wasn't used because it's nearly >> useless. > > What? See my earlier report that no IBM operating system could > turn on the ASCII bit. > > The ASCII feature would have been useful in talking to ASCII teletypes. > >> 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), > > no? Look at page 57. > > ED, EDMK, TR, TRT, etc etc are all in this manual. See Bitsavers. > >> 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. > > It did. Both EBCDIC and ASCII. > > But, as I reported earlier, no IBM operating system permitted the > ASCII bit to be set.
