I clearly remember the first (L faster than LH on some machines) but can't comment on the second (64 v. 32).
Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Tom Marchant Sent: Thursday, July 20, 2006 12:22 PM To: [email protected] Subject: Re: 64 bits is a really big number! On Thu, 20 Jul 2006 18:29:48 +0000, john gilmore <[EMAIL PROTECTED]> wrote: > >Higher fetch width is "good", but it can have odd side effects. There were >System/360 models for which Load Halfword (LH) was slower than Load (L) not >just because of sign propagation but also because LH fetched four or eight >bytes from storage two or six of which then had to be discarded. > >Analogously, there are z/Architecture situations in which eight-byte >(64-bit) instructions are faster than their four-byte (32-bit) variants. > Are you sure? ---------------------------------------------------------------------- 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
