Path: utzoo!mnetor!uunet!husc6!linus!alliant!lackey
From: lackey@Alliant.COM (Stan Lackey)
Newsgroups: comp.arch
Subject: Re: 44-bit 370 virtual addressing
Message-ID: <1261@alliant.Alliant.COM>
Date: 22 Feb 88 16:26:56 GMT
References: <488@taux01.UUCP>
Reply-To: lackey@alliant.UUCP (Stan Lackey)
Organization: Alliant Computer Systems, Littleton, MA
Lines: 21

In article <488@taux01.UUCP> yuval@taux01.UUCP (Gideon Yuval) writes:
>IBM has just announced their 44-bit-virtual-address extension to the 370
>architecture (known as ESA/370, short for Extended Storage Architecture).
>Anyone got hard facts on what the ESA/370 architecture looks like?

This information was presented at the Supercomputer Conference last year.
The talk was to present the Vector Facility, but there was lots of
background information on the Extended Architecture given as well.

The 44-bit addressing applies to the Expanded Storage, a RAM-based paging
"device" behind the Central Storage unit (i.e., main memory).  Physical 
addressing in Central Storage is 2**31 bytes, while Expanded Storage is 
architecturally defined as 2**31 PAGES (page size is 4K bytes).  Expanded 
Storage uses ports supplied in addition to the channels, and it was claimed 
that paging between Central Storage and Expanded Storage averages over
60 MBytes/sec.

This accounts for 44 bits of physical addressing.  If there is really 44 bits
of virtual addressing, it was beyond that that was presented.

-Stan Lackey