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 02:50:36 -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 001AcWw7011865; Wed, 1 Jan 2020 05:41:42 -0500 Received: from outgoing-exchange-1.mit.edu (OUTGOING-EXCHANGE-1.MIT.EDU [18.9.28.15]) by PCH.mit.edu (8.14.7/8.12.8) with ESMTP id 001AcUls011823 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Wed, 1 Jan 2020 05:38:30 -0500 Received: from OC11EXEDGE3.EXCHANGE.MIT.EDU (OC11EXEDGE3.EXCHANGE.MIT.EDU [18.9.3.21]) by outgoing-exchange-1.mit.edu (8.14.7/8.12.4) with ESMTP id 001Aco1E015783 for ; Wed, 1 Jan 2020 05:38:50 -0500 Received: from oc11exhyb4.exchange.mit.edu (18.9.1.100) by OC11EXEDGE3.EXCHANGE.MIT.EDU (18.9.3.21) with Microsoft SMTP Server (TLS) id 14.3.439.0; Wed, 1 Jan 2020 05:37:30 -0500 Received: from oc11exhyb3.exchange.mit.edu (18.9.1.99) by oc11exhyb4.exchange.mit.edu (18.9.1.100) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Wed, 1 Jan 2020 05:38:29 -0500 Received: from NAM11-DM6-obe.outbound.protection.outlook.com (104.47.57.176) by oc11exhyb3.exchange.mit.edu (18.9.1.99) with Microsoft SMTP Server (TLS) id 15.0.1395.4 via Frontend Transport; Wed, 1 Jan 2020 05:38:29 -0500 Received: from SN2PR01CA0045.prod.exchangelabs.com (2603:10b6:800::13) by SN6PR0102MB3536.prod.exchangelabs.com (2603:10b6:805:10::30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2581.11; Wed, 1 Jan 2020 10:38:28 +0000 Received: from CO1NAM03FT063.eop-NAM03.prod.protection.outlook.com (2a01:111:f400:7e48::205) by SN2PR01CA0045.outlook.office365.com (2603:10b6:800::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2602.10 via Frontend Transport; Wed, 1 Jan 2020 10:38:27 +0000 Received: from mail-ed1-f51.google.com (209.85.208.51) by CO1NAM03FT063.mail.protection.outlook.com (10.152.81.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2581.11 via Frontend Transport; Wed, 1 Jan 2020 10:38:27 +0000 Received: by mail-ed1-f51.google.com with SMTP id f8so36858162edv.2 for ; Wed, 01 Jan 2020 02:38:27 -0800 (PST) From: RussellMc To: Microcontroller discussion list - Public. CC: ApptechNZ , RossGMail , "ken@elecsyn.com" Sender: "piclist-bounces@mit.edu" Date: Wed, 1 Jan 2020 02:37:48 -0800 Subject: [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: AdXAkU02SGlRObEATTGWMEincnm3OA== Message-ID: List-Help: List-Subscribe: , List-Unsubscribe: , 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 209.85.208.51 as permitted sender) receiver=protection.outlook.com; client-ip=209.85.208.51; helo=mail-ed1-f51.google.com; dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to:cc; bh=sa93JP6WwDiEnpoY81NEQS6RdC9Fw1MrIh8+yxB7ybM=; b=g6rkWasz4oafmzKYQy9kp7WlqJqJ/0/GJ+033eixcXIOwn4Bq3Ber73vpItS3MXVke npgkVlObRO3w4UNvMch3JYFsZsrcfeb+L8zpl89/8xPKcd9iSoeXwo6oYBpKW1NTyLS7 pggf0aaioWnvWEipJnR2R4NVuq/YSItKJdm5HXqZwQ8hJVbiArTJv50C+qL+GFyW3dba byuV/G6gfrP++pyrwVl/AlSdi4mTSxodImLaLN+EW+GzAc1ql9XdFC1IK8zeqvhGCJt5 yaOKy939+W5utW3K1+fzBuUFMq/P8yi9lU5JgFh/EROb92ZvinyWFvTE0b/4hik9eC4r q9EQ== authentication-results: spf=pass (sender IP is 209.85.208.51) 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:a50:aacd:: with SMTP id r13mr81670920edc.129.1577875104663; Wed, 01 Jan 2020 02:38:24 -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 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-c= pu-run-at-only-3-25-mhz --=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 .