Article View: alt.folklore.computers
Article #618457Re: S/360 addressing, not Honeywell 200
From: Andrew Swallow
Date: Thu, 01 Feb 2018 02:39
Date: Thu, 01 Feb 2018 02:39
16 lines
2669 bytes
2669 bytes
On 29/01/2018 15:14, Scott Lurndal wrote:
> Charles Richmond <nume...@aquaporin4.com> writes:
{snip}
>> How does that compare with the time for exclusive-oring the resister
>> with itself??? On the Intel 8080, that was the fastest way to zero the
>> accumulator...
>
> That doesn't necessarily mean that the 8080 (and successors through Haswell)
> actually do the xor. Simply recognizing that the two registers are identical
> would be sufficient to drive the result to zero.
>
The 8080 was so simple that it would have performed the xor. That sort
of optimisations would have need chips with many more gates. An xor only
takes a single clock cycle anyway.
Technical Details
Message-ID:
<zbudnRzCMdl-4O_HnZ2dnUU78IXNnZ2d@giganews.com>Path:
mbox-mo1.pugleaf.net!n14ni851wmi.0!nntp.google.com!goblin3!goblin2!goblin.stu.neva.ru!weretis.net!feeder4.news.weretis.net!border2.nntp.ams1.giganews.com!nntp.giganews.com!buffer2.nntp.ams1.giganews.com!news.giganews.com.POSTED!not-for-mailReferences:
<65g3r9$8gg@bgtnsc03.worldnet.att.net> <p4cn29$fhm$1@dont-email.me> <p4d45k$f8e$1@dont-email.me> <b204534e-f56c-4b29-a177-dd66c2410b6d@googlegroups.com> <p4j0er$2im8$1@gal.iecc.com> <p4j5vb$u75$3@dont-email.me> <p4j8ki0ho2@news6.newsguy.com> <p4l4pn$17i$1@dont-email.me> <ZSGbC.1722$Ia3.59@fx44.iad>Show Full Headers
Complete Article Headers
X-Received: by 10.223.139.86 with SMTP id v22mr3733715wra.11.1517452773134; Wed, 31 Jan 2018 18:39:33 -0800 (PST) X-BeenThere: alt.folklore.computers@googlegroups.com Received: by 10.223.161.208 with SMTP id v16ls860377wrv.4.gmail; Wed, 31 Jan 2018 18:39:32 -0800 (PST) X-Received: by 10.28.239.20 with SMTP id n20mr2273874wmh.23.1517452772591; Wed, 31 Jan 2018 18:39:32 -0800 (PST) Path: mbox-mo1.pugleaf.net!n14ni851wmi.0!nntp.google.com!goblin3!goblin2!goblin.stu.neva.ru!weretis.net!feeder4.news.weretis.net!border2.nntp.ams1.giganews.com!nntp.giganews.com!buffer2.nntp.ams1.giganews.com!news.giganews.com.POSTED!not-for-mail NNTP-Posting-Date: Wed, 31 Jan 2018 20:39:31 -0600 Subject: Re: S/360 addressing, not Honeywell 200 Newsgroups: alt.folklore.computers References: <65g3r9$8gg@bgtnsc03.worldnet.att.net> <p4cn29$fhm$1@dont-email.me> <p4d45k$f8e$1@dont-email.me> <b204534e-f56c-4b29-a177-dd66c2410b6d@googlegroups.com> <p4j0er$2im8$1@gal.iecc.com> <p4j5vb$u75$3@dont-email.me> <p4j8ki0ho2@news6.newsguy.com> <p4l4pn$17i$1@dont-email.me> <ZSGbC.1722$Ia3.59@fx44.iad> From: Andrew Swallow <am.sw...@btinternet.com> Date: Thu, 1 Feb 2018 02:39:32 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: <ZSGbC.1722$Ia3.59@fx44.iad> Message-ID: <zbudnRzCMdl-4O_HnZ2dnUU78IXNnZ2d@giganews.com> Lines: 16 X-Usenet-Provider: http://www.giganews.com X-Trace: sv3-dHv04UyBulcVGxbfciytpXSsBUrgd5oKq+6moPEhtcvOsLBPbz6dQjI1kkPFC+ISNXE/vDePlrsSVh1!2LquH6w8PDthUsF3GQVWujZsZzcArL1lqxExqLrjgoh13MfbMjTW3HAEyctJAddQuHgygT2Thq4= X-Complaints-To: ab...@giganews.com X-DMCA-Notifications: http://www.giganews.com/info/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 X-Original-Bytes: 2146 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit