{"id":9438,"date":"2025-02-08T14:58:35","date_gmt":"2025-02-08T13:58:35","guid":{"rendered":"https:\/\/retrofixer.it\/?p=9438"},"modified":"2025-05-13T12:26:56","modified_gmt":"2025-05-13T10:26:56","slug":"rom-minerva","status":"publish","type":"post","link":"https:\/\/retrofixer.it\/en\/rom-minerva\/","title":{"rendered":"Minerva ROM"},"content":{"rendered":"
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Let’s make a ROM for the Sinclair QL<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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The Minerva firmware for the Sinclair QL lets you test the RAM at start-up and provides an updated operating system for this computer.
The QL uses dated memory chips, and to replace them with new EPROMs you need to adapt the pins and more: the CS signal on the old chips was active high, whereas on these it’s the opposite.<\/p>

So the signal needs to be inverted. You can do this with an inverter gate, but these often come in packages of 6 gates in DIP format, or as a single gate in some SMD formats. To simplify the circuit I used a simple transistor to invert the signal.<\/p>

Below is the schematic I made<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\"minerva\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Now let’s make the PCB with the help of PCBWAY<\/a>
Through this <\/span>Link<\/a> you can find the project.<\/span><\/p>\n

You can download the Minerva firmware here:
https:\/\/dilwyn.qlforum.co.uk\/qlrom\/index.html<\/a><\/p>\n

I used version 1.98<\/p>\n

If you need to decode the codes it shows you in case of a RAM fault, you can go to this page:
https:\/\/retrofixer.it\/ql-minerva-ram-decode\/<\/a>
\"Screen_Minerva\"<\/a> <\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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You can also find all the components you need on the page\u00a0GitHub<\/a><\/p>

A THT version has now been added too, to make assembly easier for everyone without using SMD components.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\"Minerva\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Finally, if you want to see how it’s made and how it performs in an actual test, don’t miss this video.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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<\/div>\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>","protected":false},"excerpt":{"rendered":"

Realiziamo una ROM per il Sinclair QL Il firmware Minerva per Sinclair QL permette di testare le ram all’avvio e offre un sistema operativo aggiornato per [\u2026]<\/span><\/p>\n","protected":false},"author":1,"featured_media":9441,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[19,62],"tags":[519,517,518,452,309,251],"class_list":["post-9438","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-computer","category-sinclair","tag-firmware","tag-minerva","tag-os","tag-ql","tag-rom","tag-sinclair"],"_links":{"self":[{"href":"https:\/\/retrofixer.it\/en\/wp-json\/wp\/v2\/posts\/9438","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/retrofixer.it\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/retrofixer.it\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/retrofixer.it\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/retrofixer.it\/en\/wp-json\/wp\/v2\/comments?post=9438"}],"version-history":[{"count":10,"href":"https:\/\/retrofixer.it\/en\/wp-json\/wp\/v2\/posts\/9438\/revisions"}],"predecessor-version":[{"id":9977,"href":"https:\/\/retrofixer.it\/en\/wp-json\/wp\/v2\/posts\/9438\/revisions\/9977"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/retrofixer.it\/en\/wp-json\/wp\/v2\/media\/9441"}],"wp:attachment":[{"href":"https:\/\/retrofixer.it\/en\/wp-json\/wp\/v2\/media?parent=9438"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/retrofixer.it\/en\/wp-json\/wp\/v2\/categories?post=9438"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/retrofixer.it\/en\/wp-json\/wp\/v2\/tags?post=9438"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}