On Mon, 20 Oct 2008 09:57:12 -0700, Edward Jaffe wrote: >Mohammad Khan wrote: >> And why was it expected to be 63 bit ? Was there an expectation that one >> bit will be used to distinguish a 63 bit address from 31 / 24 bit addresses ? > No, because there was no prior convention of using a doubleword to contain a 31-bit address.
>During the early discussions, many people expected ESAME to implement >63-bit addressing for reasons similar to why XA/370, ESA/370, and >ESA/390 implemented 31-bit and not 32-bit addressing. > I thought 31-bit was for compatibility with existing exploitation of the sign bit; but there was no legacy convention of using the sign bit of shorter addresses stored in a doubleword to preserve compatibility with. -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
