IBM Mainframe Discussion List <[email protected]> wrote on 06/27/2008 10:09:21 AM:
> And let's not forget to mention why these microcode assists were > added to MVS in the first place -- to make a version of MVS (MVS/SE, > MVS/SP, etc.) that would not run on "clones" like Amdahl. > > Now that there are effectively no more "clones" IBM can simply remove them? > > --- On Fri, 6/27/08, Peter Relson <[EMAIL PROTECTED]> wrote: > > > From: Peter Relson <[EMAIL PROTECTED]> > > Subject: Re: Op codes removed from z/10 > > To: [email protected] > > Date: Friday, June 27, 2008, 5:25 AM > > >It could be as simple as "the current > > >systems are so fast that maintaining the microcode and > > the microcode > > >space is no longer cost effective." > > > > Right on target. > > > > These were never instructions intended for use other than > > by the operating > > system, and the operating system no longer needed them (due > > to the speed > > situation) and (for example) it was not cost-effective to > > enhance them for > > z/Architecture. "Military secrets are the most fleeting of all." -- Spock, The Enterprise Incident, stardate 5027.4, Episode 59 The second most fleeting might be the marketing advantage provided by microcode assists. What one vendor can do in microcode, another usually can replicate in short order. So any such advantage from these assists would have run its course a few decades ago. On horizontally microcoded machines, it was possible to obtain a performance benefit in some cases by providing microcode which could implement a frequently used code sequence faster by using some hardware parallelism that was not available to the general instruction set. That is not the case on IBM processors of the past decade, and in fact using the lock assists had become slower than not using them. Jim Mulder z/OS System Test IBM Corp. Poughkeepsie, NY ---------------------------------------------------------------------- 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
