From: "David G. Conroy" Newsgroups: alt.sys.pdp10 Subject: KS10, XCT, and JRSTF Organization: Used only for posts to newsgroups X-Newsreader: Microsoft Outlook Express Macintosh Edition - 4.5 (0410) Mime-version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-transfer-encoding: 7bit Lines: 5 Message-ID: NNTP-Posting-Host: 64.171.7.165 X-Complaints-To: abuse@prodigy.net X-Trace: newssvr14.news.prodigy.com 1019282349 ST000 64.171.7.165 (Sat, 20 Apr 2002 01:59:09 EDT) NNTP-Posting-Date: Sat, 20 Apr 2002 01:59:09 EDT X-UserInfo1: Q[R_PJONYJPOBQDYMBCD^VX@WB]^PCPDLXUNNHXIJYWZUYICD^RAQBKZQTZTX\_I[^G_KGFNON[ZOE_AZNVO^\XGGNTCIRPIJH[@RQKBXLRZ@CD^HKANYVW@RLGEZEJN@\_WZJBNZYYKVIOR]T]MNMG_Z[YVWSCH_Q[GPC_A@CARQVXDSDA^M]@DRVUM@RBM Date: Sat, 20 Apr 2002 05:59:09 GMT Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-out.spamkiller.net!propagator2-maxim!propagator-maxim!news-in.spamkiller.net!xmission!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!newsfeed.cwix.com!newscon02.news.prodigy.com!newsmst01.news.prodigy.com!prodigy.com!postmaster.news.prodigy.com!newssvr14.news.prodigy.com.POSTED!not-for-mail Xref: chonsp.franklin.ch alt.sys.pdp10:11190 The KS10 microcode, on JRSTF/JEN, re-does the EA calculation in a way which preserves the LH flags, assuming that the JRSTF/JEN is at PC-1. Does this do the wrong thing if you XCT the JRSTF/JEN, or am I misreading something ... ###### From: klh@panix.com (Ken Harrenstien) Newsgroups: alt.sys.pdp10 Subject: Re: KS10, XCT, and JRSTF Date: 20 Apr 2002 03:51:33 -0400 Organization: PANIX Public Access Internet and UNIX, NYC Lines: 20 Message-ID: References: NNTP-Posting-Host: panix2.panix.com X-Trace: reader1.panix.com 1019289023 28249 166.84.1.2 (20 Apr 2002 07:50:23 GMT) X-Complaints-To: abuse@panix.com NNTP-Posting-Date: Sat, 20 Apr 2002 07:50:23 +0000 (UTC) Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!feedme.news.mediaways.net!newsfeeds.belnet.be!news.belnet.be!fr.clara.net!heighliner.fr.clara.net!proxad.net!yellow.newsread.com!netaxs.com!newsread.com!panix!panix2.panix.com!not-for-mail Xref: chonsp.franklin.ch alt.sys.pdp10:11192 In article , David G. Conroy wrote: >The KS10 microcode, on JRSTF/JEN, re-does the EA calculation >in a way which preserves the LH flags, assuming that the JRSTF/JEN is >at PC-1. Does this do the wrong thing if you XCT the JRSTF/JEN, >or am I misreading something ... It's certainly possible; I have spotted a few other potential bugs. Although for things like this, testing on a real machine is the simplest and sometimes only way to know for sure. Especially on the KL where the hardware added many side effects not visible in the microcode. FWIW the KLH10 implementation similarly restarts EA evaluation from the PC (the instruction is sufficiently rare that it's not worth saving the EA calc results in the main loop), but does the "right thing" by tracking XCT chains. It would not surprise me if nothing ever depended on this, of course. --Ken