On Sat, Oct 10, 2009 at 6:25 PM, Ed Gould <ps2...@yahoo.com> wrote: > A long time ago and far far away (1980's ?) I was in a MVS debugging course > (at IBM).I asked a question of the instructor and got an answer which I > looked at as a non answer.Though the years I have asked several IBM type's > and got a "I don't know either" reply. > I thought I would ask here as this group had a broad background and will > probably have the correct answer. > There is a bit reserved in the PSW for "ASCII". Does anyone know if this was > ever used and if so what was it used for. If it wasn't used does anyone know > what it was planned to use for?
The intent was for S/360 to be usable in ASCII; that never happened. At some point the bit was reassigned (S/370 according to http://www.cbttape.org/~jmorrison/s370asm/html/tut-S370-design-001.html, which mentions the bit). Another paper states: It is worth noting that IBM seriously considered adoption of ASCII as its method for internal storage of character data for the System/360. The American Standard Code for Information Interchange was approved in 1963 and supported by IBM. However the ASCII code set was not compatible with the BCDIC used on a very large installed base of support equipment, such as the IBM 026. Transition to an incompatible character set would have required any adopter of the new IBM System/360 to also purchase or lease an entirely new set of peripheral equipment; this would have been a deterrence to early adoption. I bet Lynn will have a bunch more references... ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
