Received: from PCH.mit.edu (18.7.21.50) by mail.efplus.com (192.168.0.8) with Microsoft SMTP Server (TLS) id 8.3.485.1; Wed, 1 Jan 2020 09:12:07 -0800 Received: from PCH.MIT.EDU (localhost.localdomain [127.0.0.1]) by PCH.mit.edu (8.14.7/8.12.8) with ESMTP id 001H0sRl032085; Wed, 1 Jan 2020 12:03:38 -0500 Received: from outgoing-exchange-7.mit.edu (OUTGOING-EXCHANGE-7.MIT.EDU [18.9.28.58]) by PCH.mit.edu (8.14.7/8.12.8) with ESMTP id 001H0qjs032077 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Wed, 1 Jan 2020 12:00:52 -0500 Received: from w92exedge4.exchange.mit.edu (W92EXEDGE4.EXCHANGE.MIT.EDU [18.7.73.16]) by outgoing-exchange-7.mit.edu (8.14.7/8.12.4) with ESMTP id 001H0ku9006096 for ; Wed, 1 Jan 2020 12:00:47 -0500 Received: from oc11expo28.exchange.mit.edu (18.9.4.99) by w92exedge4.exchange.mit.edu (18.7.73.16) with Microsoft SMTP Server (TLS) id 15.0.1293.2; Wed, 1 Jan 2020 11:58:49 -0500 Received: from oc11exhyb5.exchange.mit.edu (18.9.1.110) by oc11expo28.exchange.mit.edu (18.9.4.99) with Microsoft SMTP Server (TLS) id 15.0.1365.1; Wed, 1 Jan 2020 12:00:33 -0500 Received: from NAM11-CO1-obe.outbound.protection.outlook.com (104.47.56.170) by oc11exhyb5.exchange.mit.edu (18.9.1.110) with Microsoft SMTP Server (TLS) id 15.0.1395.4 via Frontend Transport; Wed, 1 Jan 2020 12:00:33 -0500 Received: from SN2PR01CA0062.prod.exchangelabs.com (2603:10b6:800::30) by BYAPR01MB4134.prod.exchangelabs.com (2603:10b6:a03:58::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2581.12; Wed, 1 Jan 2020 17:00:32 +0000 Received: from DM3NAM03FT046.eop-NAM03.prod.protection.outlook.com (2a01:111:f400:7e49::202) by SN2PR01CA0062.outlook.office365.com (2603:10b6:800::30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2602.12 via Frontend Transport; Wed, 1 Jan 2020 17:00:32 +0000 Received: from mail-ed1-f49.google.com (209.85.208.49) by DM3NAM03FT046.mail.protection.outlook.com (10.152.83.87) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2602.11 via Frontend Transport; Wed, 1 Jan 2020 17:00:31 +0000 Received: by mail-ed1-f49.google.com with SMTP id b8so37349248edx.7 for ; Wed, 01 Jan 2020 09:00:31 -0800 (PST) From: David C Brown To: Microcontroller discussion list - Public. Sender: "piclist-bounces@mit.edu" Date: Wed, 1 Jan 2020 09:00:20 -0800 Subject: Re: [OT]:: Why did the ZX80 CPU run at only 3.25- MHz Thread-Topic: [OT]:: Why did the ZX80 CPU run at only 3.25- MHz Thread-Index: AdXAxplgfd28r09rRmCg5P8o1W5sMg== Message-ID: References: List-Help: List-Subscribe: , List-Unsubscribe: , In-Reply-To: Reply-To: Microcontroller discussion list - Public. Accept-Language: en-US X-MS-Exchange-Organization-AuthAs: Anonymous X-MS-Exchange-Organization-AuthSource: TS500.efplus4.local X-MS-Has-Attach: X-Auto-Response-Suppress: All X-MS-Exchange-Organization-SenderIdResult: Pass X-MS-Exchange-Organization-PRD: mit.edu X-MS-TNEF-Correlator: received-spf: Pass (protection.outlook.com: domain of gmail.com designates 209.85.208.49 as permitted sender) receiver=protection.outlook.com; client-ip=209.85.208.49; helo=mail-ed1-f49.google.com; dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=5aZb9rwfAawmlzLdAGoBkr5rKJVCAet4oE5FsqQh76c=; b=sOOcyt4PcuYX1MB6tgcEyCQwNbiuMHzKPnnjgOLlEz8sLSfwhhc/O+RjK32rm8E97g HMv0AAHeajcWLL7MgbeD8NisgC24WxK6+kXqofUDPuppZsZbo9ge0z9l9hs4qN1sTB5X pMB/o/il3XIgIBE4uRZ9h2AAUjZGUGtUAEKvPab+7skGZGuV7pxXvDQI0NKfgbe81+1F GijhclSvk3PoPauPJSeYVR3HlxxLafdvg6pLi6DX0+SYmAQ0yEi+/jKdXa8CcM4nGs6A De8XtG0PrHxwY0c4TPexo3G1TnKKY0MGdBdSpMDW5iPVktAH1evNcmNsPtmAZfQHPTXY oLaA== authentication-results: spf=pass (sender IP is 209.85.208.49) smtp.mailfrom=gmail.com; mit.edu; dkim=pass (signature was verified) header.d=gmail.com;mit.edu; dmarc=pass action=none header.from=gmail.com;compauth=pass reason=100 errors-to: piclist-bounces@mit.edu list-id: "Microcontroller discussion list - Public." list-post: x-beenthere: piclist@mit.edu x-mailman-version: 2.1.6 x-received: by 2002:a17:906:3195:: with SMTP id 21mr84297157ejy.207.1577898029872; Wed, 01 Jan 2020 09:00:29 -0800 (PST) x-topics: [OT] x-content-filtered-by: Mailman/MimeDel 2.1.6 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 The simple answer - hinted at in the link - is because it was designed Clive Sinclair the man who designed "one of the great marketing bombs of postwar British industry " the C5 eclectic vehicle (There is a mis-correction for electric there but I think it fair to let it stand.) __________________________________________ David C Brown 43 Bings Road Whaley Bridge High Peak Phone: 01663 733236 Derbyshire eMail: dcb.home@gmail.com SK23 7ND web: www.bings-knowle.co.uk/dcb *Sent from my etch-a-sketch* On Wed, 1 Jan 2020 at 10:42, RussellMc wrote: > IF Q: What's a ZX80? > THEN A: This is not the post you want, nothing to see here, move along. > ELSE > > Stack Exchange retrocomputing: > > Why did the ZX80 CPU run at only 3.25- MHz > > > Well discussed elsewhere but there is enough relevant peripheral material > to be of possible interest > > > > https://retrocomputing.stackexchange.com/questions/13208/why-did-the-zx80= -cpu-run-at-only-3-25-mhz > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .