Predned\u00e1vnom som sa prehrab\u00e1val v svojich arch\u00edvoch a natrafil som na oskenovan\u00e9 AR s popisom na v\u00fdrobu klonu ZX spectra nazvan\u00e9ho Mistrum. Dos\u0165 som si to poobzeral a tak ma to zaujalo, \u017ee som sa rozhodol trocha ho pripomen\u00fa\u0165. Mistrum je na vtedaj\u0161iu dobu nesporne zauj\u00edmav\u00fd klon ZX Spectra. Jeho vznik pravdepodobne zapr\u00ed\u010dinila jednak vysok\u00e1 cena origin\u00e1lnych ZXS a vdruhom rade ich slab\u00e1 dostupnos\u0165. Po\u010din v.d. Skalica – Didaktik Gama – bol v prv\u00fdch modeloch sk\u00f4r rozpa\u010ditou sk\u00fa\u0161kou trhu a z\u00e1ujmu obyvate\u013estva a \u010dloveka aspo\u0148 trocha znal\u00e9ho hw pri poh\u013eade na dosku modelu ’87 divne zamraz\u00ed vzadu na krku. A t\u00ed e\u0161te znalej\u0161\u00ed len zalomia rukami a pokr\u00fatia hlavou. Toto sa asi stalo aj autorom Mistruma a tak si ZX Spectrum vyrobili in\u00e1\u010d a hlavne pod\u013ea seba. Ke\u010f nahliadneme do ich \u010dl\u00e1nku a popozer\u00e1me si dolo\u017een\u00e9 sch\u00e9my, mus\u00ed n\u00e1m by\u0165 jasn\u00e9, \u017ee chlap\u00edci sa naozaj vyznali a pr\u00e1cu odviedli poctivo, vr\u00e1tane a\u017e \u00fachylne ve\u013ek\u00e9ho plo\u0161\u00e1ku, hoci vzh\u013eadom na po\u010det IO je t\u00e1 ve\u013ekos\u0165 nutnos\u0165ou. Na \u010do by som chcel upozorni\u0165, je hlavne netradi\u010dn\u00e1 architekt\u00fara. Ako vieme, no\u010dnou morou v\u0161etk\u00fdch ZXS klonov je ULA. Skalica si na DG pr\u00e1cu u\u013eah\u010dila t\u00fdm, \u017ee za drah\u00e9 dev\u00edzy nak\u00fapila origin\u00e1lne ULY. S\u00edce to zjednodu\u0161ilo plo\u0161\u00e1k, ale predra\u017eilo fin\u00e1lny v\u00fdrobok a obmedzilo opravite\u013enos\u0165 v neskor\u0161ej dobe. Rusi sa dali \u0165a\u017e\u0161ou cestou a v bezpo\u010dte klonov ktor\u00e9 u nich vznikli, n\u00e1jdeme viac \u010di menej podaren\u00fa n\u00e1hradu ULY tvoren\u00fa viacer\u00fdmi be\u017en\u00fdmi IO, \u010do je pod\u013ea m\u0148a lep\u0161ia cesta, lebo to zaru\u010duje vysok\u00fa \u017eivotnos\u0165 a \u013eahk\u00fa opravite\u013enos\u0165 a ur\u010dite to vyva\u017euje nev\u00fdhodu v podobe extr\u00e9mne vysok\u00e9ho po\u010dtu IO na plo\u0161\u00e1ku. Autori Mistruma v\u0161ak za\u0161li e\u0161te \u010falej a navrhli si vlastn\u00fd po\u010d\u00edta\u010d pri zachovan\u00ed kompatibility so ZXS. Prinieslo to nieko\u013eko v\u00fdhod. Po\u010det IO sa zmen\u0161il na nevyhnutn\u00e9 minimum, o 3% sa zv\u00fd\u0161il opera\u010dn\u00fd v\u00fdkon, o\u0161etrili sa zn\u00e1me chyby ULY, je k dispoz\u00edcii cel\u00fdch 64kB RAM v\u010faka allram m\u00f3du, zbernica je posilnen\u00e1, vstup a v\u00fdstup pre MGF je oddelen\u00fd, nech\u00fdbaj\u00fa tla\u010d\u00edtka NMI a RESET, pribudla mo\u017enos\u0165 invertova\u0165 obrazov\u00fd sign\u00e1l, \u010di regulova\u0165 hlasitos\u0165 vstavan\u00e9ho reproduktora a p\u00e1r \u010fal\u0161\u00edch vychyt\u00e1vok, napr. resetovac\u00ed obvod je koncipovan\u00fd tak, \u017ee pam\u00e4tiam pri resete nevypadne refresh a tak si zachov\u00e1vaj\u00fa obsah. Po\u010d\u00edta\u010dov\u00e1 \u010das\u0165 Mistruma vych\u00e1dza zo ZXS, av\u0161ak je vylep\u0161en\u00e1 o u\u017e spom\u00ednan\u00e9 posilova\u010de zbernice a in\u00e1\u010d tu u\u017e nen\u00e1jdeme ni\u010d zvl\u00e1\u0161tne. Prekvapenie nast\u00e1va, ke\u010f si obzrieme \u010das\u0165, ktor\u00e1 sa star\u00e1 o zobrazovanie. Autori Mistruma to vyrie\u0161ili \u00faplne \u0161alam\u00fansky a to tak, \u017ee o zobrazovanie sa star\u00e1 pridan\u00e1 8kB SRAM do ktorej sa hardv\u00e9rovo kop\u00edruj\u00fa d\u00e1ta z oblasti kde m\u00e1 norm\u00e1lne ZXS VRAM. Bonus spo\u010d\u00edva v tom, \u017ee t\u00fdm p\u00e1dom sa dalo vyrie\u0161i\u0165 \u010dasovanie CPU a "ULY" tak, \u017ee nie je potrebn\u00e9 pozastavova\u0165 CPU v dobe, ke\u010f chce do RAM pristupova\u0165 "ULA", tak\u017ee sa vytratil slowram efekt. Toto geni\u00e1lne rie\u0161enie u\u0161etrilo a\u017e 30% IO, ktor\u00e9 by sa inak starali o zobrazovanie sp\u00f4sobom ak\u00fdm to rob\u00ed origin\u00e1lne ZXS. Vznikol tak unik\u00e1tny klon ZXS, ktor\u00fd sa mohol s\u00e9riovo vyr\u00e1ba\u0165 z dom\u00e1cich s\u00fa\u010diastok za zlomok ceny ZXS a je \u0161koda, \u017ee Skalica sa rozhodla \u00eds\u0165 cestou Didaktiku M, preto\u017ee autori Skalici Mistrum pon\u00fakli ako n\u00e1hradu za nie ve\u013emi vydaren\u00fd DG. V\u010faka ni\u017e\u0161ej cene, ktor\u00fa by s\u00e9riovo vyr\u00e1ban\u00e9 Mistrum ur\u010dite malo, by sa mo\u017eno bola roz\u0161\u00edrila Speccym\u00e1nia e\u0161te viac, a dne\u0161n\u00e9 u\u017e dos\u0165 \u00faboh\u00e9 rady spectristov by boli ur\u010dite v\u00e4\u010d\u0161ie. My sme tak pri\u0161li o lacn\u00e9ho, odoln\u00e9ho a \u013eahko opravite\u013en\u00e9ho \u010deskoslovensk\u00e9ho bra\u010deka ZX Spectra, a namiesto neho sme kupovali po\u010d\u00edta\u010de podivn\u00e9ho n\u00e1vrhu s ruskou ulou. No a ke\u010f\u017ee som \u010dlovek v celku tvoriv\u00fd, prekreslil som Mistrum do Eeaglu. S\u00fabory n\u00e1jdete u m\u0148a na str\u00e1nke (
http:\/\/z00m.speccy.cz<\/a>) v sekcii hardware. Kto sa nud\u00ed, m\u00f4\u017ee naroutova\u0165 dosku \ud83d\ude42 A ako spr\u00e1vne podotkol jeden z \u010ditate\u013eov \u010dl\u00e1nku, kon\u0161trukcia a popis po\u010d\u00edta\u010da Mistrum boli publikovan\u00e9 v \u010dasopise Amat\u00e9rsk\u00e9 radio B (modr\u00e1 rada) 38(1) 2-39 (1989). S\u00fa\u010das\u0165ou je aj podrobn\u00fd popis funkcie ZX Spectra.<\/div>\n","protected":false},"excerpt":{"rendered":"Zabudnut\u00e9 \u010deskoslovensk\u00e9 ZX Spectrum?<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22],"tags":[],"class_list":["post-252610","post","type-post","status-publish","format-standard","hentry","category-zx-spectrum"],"_links":{"self":[{"href":"https:\/\/blog.darkbyte.sk\/index.php?rest_route=\/wp\/v2\/posts\/252610","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.darkbyte.sk\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.darkbyte.sk\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.darkbyte.sk\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.darkbyte.sk\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=252610"}],"version-history":[{"count":1,"href":"https:\/\/blog.darkbyte.sk\/index.php?rest_route=\/wp\/v2\/posts\/252610\/revisions"}],"predecessor-version":[{"id":929226,"href":"https:\/\/blog.darkbyte.sk\/index.php?rest_route=\/wp\/v2\/posts\/252610\/revisions\/929226"}],"wp:attachment":[{"href":"https:\/\/blog.darkbyte.sk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=252610"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.darkbyte.sk\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=252610"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.darkbyte.sk\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=252610"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}