Path: news.eternal-september.org!eternal-september.org!feeder3.eternal-september.org!news.iecc.com!.POSTED.news.iecc.com!not-for-mail From: John Levine Newsgroups: comp.arch Subject: Re: millicode, extracode, fractional PCs Date: Fri, 2 May 2025 17:26:19 -0000 (UTC) Organization: Taughannock Networks Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Date: Fri, 2 May 2025 17:26:19 -0000 (UTC) Injection-Info: gal.iecc.com; posting-host="news.iecc.com:2001:470:1f07:1126:0:676f:7373:6970"; logging-data="40729"; mail-complaints-to="abuse@iecc.com" In-Reply-To: Cleverness: some X-Newsreader: trn 4.0-test77 (Sep 1, 2010) Originator: johnl@iecc.com (John Levine) According to moi : >On 02/05/2025 16:18, EricP wrote: > >> And a paper on IBM Millicode which is kind of like Alpha PAL code >> and may be similar to Robert's mega-ops. >> >> The What and Why of System z Millicode 2012 >> https://share.confex.com/share/119/webprogram/Handout/Session11773/The%20What%20and%20Why%20of%20System%20z%20Millicode%20-%20%2311773.pdf > >Thanks for that reference. > >I struggle to see how "millicode" differs in essentials from >the "extracode" implementation of complex orders on the >Ferranti Orion & Atlas, or the ICT 1900 Series, of 60 years ago. It looks very similar. The main difference I can see from extracode is that extracode used the same hardware instruction set as normal programs but millicode has a few extra instructions not usable in normal programs. Given that that deck credited Wilkes for microcode in the 1950s I'm suprised they didn't mention extracodes. Surely they knew about it. -- Regards, John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies", Please consider the environment before reading this e-mail. https://jl.ly