1.0MO5.COMhttps://mo5.com/enrich600338<blockquote class="wp-embedded-content" data-secret="EBS2bLR1nW"><a href="https://mo5.com/en/looking-for-documentation/">Looking for documentation</a></blockquote><iframe sandbox="allow-scripts" security="restricted" src="https://mo5.com/en/looking-for-documentation/embed/#?secret=EBS2bLR1nW" width="600" height="338" title=""Looking for documentation - MO5.COM" data-secret="EBS2bLR1nW" frameborder="0" marginwidth="0" marginheight="0" scrolling="no" class="wp-embedded-content"></iframe><script type="text/javascript"> /* <![CDATA[ */ /*! This file is auto-generated */ !function(d,l){"use strict";l.querySelector&&d.addEventListener&&"undefined"!=typeof URL&&(d.wp=d.wp||{},d.wp.receiveEmbedMessage||(d.wp.receiveEmbedMessage=function(e){var t=e.data;if((t||t.secret||t.message||t.value)&&!/[^a-zA-Z0-9]/.test(t.secret)){for(var s,r,n,a=l.querySelectorAll('iframe[data-secret="'+t.secret+'"]'),o=l.querySelectorAll('blockquote[data-secret="'+t.secret+'"]'),c=new RegExp("^https?:$","i"),i=0;i<o.length;i++)o[i].style.display="none";for(i=0;i<a.length;i++)s=a[i],e.source===s.contentWindow&&(s.removeAttribute("style"),"height"===t.message?(1e3<(r=parseInt(t.value,10))?r=1e3:~~r<200&&(r=200),s.height=r):"link"===t.message&&(r=new URL(s.getAttribute("src")),n=new URL(t.value),c.test(n.protocol))&&n.host===r.host&&l.activeElement===s&&(d.top.location.href=t.value))}},d.addEventListener("message",d.wp.receiveEmbedMessage,!1),l.addEventListener("DOMContentLoaded",function(){for(var e,t,s=l.querySelectorAll("iframe.wp-embedded-content"),r=0;r<s.length;r++)(t=(e=s[r]).getAttribute("data-secret"))||(t=Math.random().toString(36).substring(2,12),e.src+="#?secret="+t,e.setAttribute("data-secret",t)),e.contentWindow.postMessage({message:"ready",secret:t},"*")},!1)))}(window,document); //# sourceURL=https://mo5.com/wp-includes/js/wp-embed.min.js /* ]]> */ </script>https://mo5.com/wp-content/uploads/2023/02/Micral-N-Users-Manual-Couverture-High.png633935By Sylvain Glaize. Translation by Sébastien Marty. Research The Micral N restoration project has been launched and given its condition, the goal to restart it seems quite feasible. But how does it work? What is the machine made of? Couldn’t we find some documentation? What we know is that the machine is built around what was back then the brand new Intel 8008. And documentation for the 8008 is available, whether the specs from Intel or a few pages on the Internet. But when it comes to studying the Micral N, things get tough. Websites that discuss the 8008 focus on other machines : SCELBI, Mark-8,… The only document you can find is a « Users Manual »  preserved by the Bitsavers project. It includes black and white photos of some boards, with captions. It’s skimpy, but it’ll do for now. And after all, a hundred technical pages still make for a good piece of reading.   The 8008 Reading the specs of the 8008 is pretty quick. The documentation is generally clear and quite detailed, presenting all the operations at each state for each instruction. Without going into too much detail, the 8008 is a 500 kHz processor (yes, five hundred kilohertz) in an 18-pin package, which processes 8-bit data and has a 14-bit address range. As 18 pins are not enough, the data are multiplexed, which is an important aspect for the Micral N architecture. The processor contains seven registers including an accumulator and an 8-level call stack, not programmatically accessible. And finally, a rudimentary interrupt system. There, the Micral N will be able to provide a slightly higher-level solution, as we will see later. It is very small but that’s only natural, since it was the first 8-bit microprocessor The Micral N The Micral N manual is a little more difficult to read, due to several factors. The first one is the age of the documentation. We do not describe a 1974 machine using 2021 vocabulary. The other factors are more annoying. What may be ascribed at first to careless reading becomes more and more obvious: there are mistakes in the manual. Those mistakes are of several different kinds: typing errors, such as confusions between 1 (one) and I (capital i), errors in the location of signals, explanations that contradict the diagrams, etc. And there are gaps, too, like some undescribed signals. Or pitfalls, such as signals translated into English in the text but written in French on the diagrams. However, this documentation is still a great tool to get started. A mental image Thanks to these readings, one can begin to form a mental image of the way the Micral N operates: a set of boards communicating with each other through a backplane bus. The boards are varied: a processor board, memory boards, communication boards for peripheral devices. Some of the boards in the association’s unit are referenced in the manual, some are not. Conversely, some boards in the manual are not present in the Micral N we’re studying. The conclusion is nevertheless obvious: this unit houses all the boards needed to run a program. Emulation […]