{"id":9333,"date":"2020-08-04T11:19:36","date_gmt":"2020-08-04T10:19:36","guid":{"rendered":"https:\/\/stevepedwards.today\/ElectronicsStuff\/?p=9333"},"modified":"2020-08-14T13:33:04","modified_gmt":"2020-08-14T12:33:04","slug":"z80-cpu-tester-julian-illet","status":"publish","type":"post","link":"https:\/\/stevepedwards.today\/ElectronicsStuff\/z80-cpu-tester-julian-illet\/","title":{"rendered":"Z80 CPU Tester &#8211; Julian Illet"},"content":{"rendered":"<p><iframe loading=\"lazy\" title=\"Flashing LEDs - Z80 Style\" width=\"1778\" height=\"1000\" src=\"https:\/\/www.youtube.com\/embed\/AZb4NLXx1aM?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<p>Testing a Mostek z80 CPU found in a Walker Sat Nav 801.<\/p>\n<p><a href=\"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-content\/uploads\/2020\/08\/3880.pdf\">3880.pdf<\/a><\/p>\n<p>Max clock = 2.5MHz<\/p>\n<p>3 the same Z80PIO chips - can't check these now.<\/p>\n<p>1 x z80 MK3880N-41RL --\u00a0 binary counting the same as the circuit above, but you need a min of 4 LEDs to start this and can go to all 16 buss pins 40-29 next to pin 28 ground and 1-5.<\/p>\n<p>You NEED to unplug completely to restart the power an arbitrary-\u00a0 amount of times due to an unknown factor, to restart the counting operation as it seems to latch some\/all of the LEDs on most times - possibly saved state or refresh cycle counts etc? That makes building this as a tester circuit invalid as is! Need to make it reset to the count state at power on somehow or have a reset type button to force it to count state? Can't find that info in the PDF or make sense of it.<\/p>\n<p>When the unit counts with 8+ LEDs, the LEDs from 8-11 flash rather than stay on to mark the power of 2 - power saving?:<\/p>\n<p>16 LEDs all lit = 2^16-1 count = 65535<\/p>\n<p>This Mostek unit doesn't get hot driving these white LEDs with no limiting resistors either.<\/p>\n<p>I added the remaining 5 blue LEDs, pins 1-5, which should give the total count to 2^16 = 65536 for this 16 bit CPU.<\/p>\n<p><iframe loading=\"lazy\" title=\"Z80 Mostek 16 bit CPU binary counter\" width=\"1778\" height=\"1000\" src=\"https:\/\/www.youtube.com\/embed\/0R-1h5Wz9-A?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<p>Found the reset pin 26 by trial and error shorts to gnd:<\/p>\n<p><iframe loading=\"lazy\" title=\"Z80 Mostek 16 bit CPU binary counter reset pin\" width=\"1778\" height=\"1000\" src=\"https:\/\/www.youtube.com\/embed\/daFN1fSCziY?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<p>It's now consistent so useful as a tester so worth building for the experience.<\/p>\n<p><iframe loading=\"lazy\" title=\"Z80 Mostek 16 bit CPU binary counter 555 timer noise removal via 100nF cap\" width=\"1778\" height=\"1000\" src=\"https:\/\/www.youtube.com\/embed\/3YSvJLVP_Kc?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<p><iframe loading=\"lazy\" title=\"Z80 Tester\/Counter All LEDs = 2^16 Binary\" width=\"1333\" height=\"1000\" src=\"https:\/\/www.youtube.com\/embed\/2UZYOLqoMxw?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Testing a Mostek z80 CPU found in a Walker Sat Nav 801. 3880.pdf Max clock = 2.5MHz 3 the same Z80PIO chips - can't check these now. 1 x z80 MK3880N-41RL --\u00a0 binary counting the same as the circuit above, but you need a min of 4 LEDs to start this and can go to <a href=\"https:\/\/stevepedwards.today\/ElectronicsStuff\/z80-cpu-tester-julian-illet\/\" class=\"more-link\">...<span class=\"screen-reader-text\">  Z80 CPU Tester &#8211; Julian Illet<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-9333","post","type-post","status-publish","format-standard","hentry","category-uncategorised"],"_links":{"self":[{"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/posts\/9333","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/comments?post=9333"}],"version-history":[{"count":25,"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/posts\/9333\/revisions"}],"predecessor-version":[{"id":9448,"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/posts\/9333\/revisions\/9448"}],"wp:attachment":[{"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/media?parent=9333"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/categories?post=9333"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/tags?post=9333"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}