From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FROM,MAILING_LIST_MULTI, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 6025 invoked from network); 27 Jul 2023 16:31:01 -0000 Received: from minnie.tuhs.org (50.116.15.146) by inbox.vuxu.org with ESMTPUTF8; 27 Jul 2023 16:31:01 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id 5FB9940BEA; Fri, 28 Jul 2023 02:30:58 +1000 (AEST) Received: from mail-pj1-x102f.google.com (mail-pj1-x102f.google.com [IPv6:2607:f8b0:4864:20::102f]) by minnie.tuhs.org (Postfix) with ESMTPS id D58A840034 for ; Fri, 28 Jul 2023 02:30:46 +1000 (AEST) Received: by mail-pj1-x102f.google.com with SMTP id 98e67ed59e1d1-26830595676so826806a91.2 for ; Thu, 27 Jul 2023 09:30:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1690475446; x=1691080246; h=cc:to:subject:message-id:date:from:references:in-reply-to :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=DI2QDwsrnsDxykG/irK880UdxKuba6Ga1mDWpSpT5gw=; b=YQTyaiHjdKSvIhlVR+M2gkXAlwIFWmVVlh+AD82E7W+PYZAndWKmLODeVUa4bAV20y SXQoRNTYSvv7S5IJrKVFURbxNALioSlaABRVt97BnsCdHLFrGkYlu2kfNAJKvcZg/dJG YQoWmYyLlPH7mTBhmlnY85aX5MQydl4RyIoFU3xs20cLpx2dhqxdEMU2XXWVPIS6ayl7 jTbE0IFJ+TlLZLbjmSrKhsiNxjSGG7UwpmSgUzPzNYd4xlRXhYXVKygVw4GiZmkvuveR sJ9y3a7F9wnHQQsQDMB01nsLeksrB1QUdvagRTCijYM7zNeXSVVMGSZEsTTJT/mNrejV 2lTg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690475446; x=1691080246; h=cc:to:subject:message-id:date:from:references:in-reply-to :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=DI2QDwsrnsDxykG/irK880UdxKuba6Ga1mDWpSpT5gw=; b=ILug9zSt9ZN8oOIFs31KCwbnttBkyv0AfB0P3M/cc2wcwoE8Reuv61BuXhjIYuDEBp PcrUQlz1KVczFMl6V16w/grQWaoy3Kl6tnwFCKKEZJKLiW7upsQiFGeTLYgkIKr2slW1 TdNQEW8NAUfGFUFb6v5griSjWBrDat24o3Yca8v36eLMjDdgMCxV0oQ9If71DtKD/vGU 8Pe4UDRVb8kbKpwwed/N/ia/hbsbRPqNCVWBmaF+zD/AosXzyhP0U3vhsBiE38NSF/ol izBwuBx40/6KVV9z4dIWRCIJA3izimZCUEVQkUWabhvu6vtcCZPHsKC2nSWavOwmUz0B cT5w== X-Gm-Message-State: ABy/qLZqobTvcYiJMnXxVIkEcz73DsdAPzI+9+LdfFOmyqanKzUxE/5L 0qWhgELmBMY8+hsdsZfRjSZ6De/4K+f0VZsXe0km/PiC X-Google-Smtp-Source: APBJJlHWhopLFRXKHbHPB9Odvd3S9q3YoUDBx1Vt2GIWnH1oH1GAxy29P7M84GXszDvwrUsx8rgkxEtKqcHEKInHvBM= X-Received: by 2002:a17:90a:eac6:b0:263:3194:d691 with SMTP id ev6-20020a17090aeac600b002633194d691mr5252110pjb.45.1690475446066; Thu, 27 Jul 2023 09:30:46 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a05:6a11:af19:b0:4c1:7ec0:eb04 with HTTP; Thu, 27 Jul 2023 09:30:45 -0700 (PDT) In-Reply-To: <20230727034350.GC92211@eureka.lemis.com> References: <20230727034350.GC92211@eureka.lemis.com> From: Paul Winalski Date: Thu, 27 Jul 2023 12:30:45 -0400 Message-ID: To: "Greg 'groggy' Lehey" Content-Type: text/plain; charset="UTF-8" Message-ID-Hash: MK474RCXNU7DXCWIACI7G334X3S4FDDE X-Message-ID-Hash: MK474RCXNU7DXCWIACI7G334X3S4FDDE X-MailFrom: paul.winalski@gmail.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: COFF X-Mailman-Version: 3.3.6b1 Precedence: list Subject: [COFF] Re: What Happened to Interdata? List-Id: Computer Old Farts Forum Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On 7/26/23, Greg 'groggy' Lehey wrote: > > That's not the way I remember it. RCA (and UNIVAC with them) and > Interdata had instruction sets that were close to the IBM instruction > set, but my recollection was that they were different enough that IBM > software wouldn't run on them. That's a different situation from > Amdahl, which was almost completely compatible. As I recall it, the RCA Specra 70 was compatible with the IBM System 360 instruction set. It thus could run S/360 user applications. And maybe OS/360? The downfall came with S/370. IBM withheld the privileged portions of the architecture (including dynamic address translation [DAT; virtual memory]) and so when OS/VS and DOS/VS came out they wouldn't run on Spectra 70. RCA was forced to develop their own OS. Over time key IBM applications such as CICS depended on new features in OS/VS and DOS/VS. It wouldn't surprise me if many of those dependencies were gratuitous. So RCA was stuck in an endless cycle of having to add new (D)OS/VS features to their own OS. The big IT customers who form this market valued stability more than the lower price for the Spectra vs. S/370, and so RCA lost its market and eventually gave up. By the time Amdahl founded his own company, the privileged side of the S/370 architecture had been revealed. The S/370 architecture allows for a restricted set of model-dependent behavior and features in areas such as control register semantics and machine check handling. The Amdahl CPUs were no different from the S/370s as one model of S/370 is from another. (D)OS/VS keeps this model-dependent code in separate modules from the bulk of the OS. Amdahl only had to provide their own set of model-dependent modules. A smaller--and tractable--task compared to what had faced RCA and Interdata at the start of the S/370 era. -Paul W.