{"id":1005,"date":"2024-02-08T06:51:25","date_gmt":"2024-02-08T06:51:25","guid":{"rendered":"http:\/\/tlindner.macmess.org\/?p=1005"},"modified":"2024-02-08T06:51:25","modified_gmt":"2024-02-08T06:51:25","slug":"coco-3-pia-2-mirror","status":"publish","type":"post","link":"https:\/\/tlindner.macmess.org\/?p=1005","title":{"rendered":"CoCo 3 PIA 2 Mirror"},"content":{"rendered":"<p>The second PIA has a smaller mirror in the CoCo 3 than the CoCo 1\/2. It goes from $FF20 to $FF2F. The CoCo 1\/2 mirror is from $FF20 to $FF3F.<\/p>\n<p>Recently I was challenged to find a citation for this information. But I could not. <a href=\"https:\/\/colorcomputerarchive.com\/repo\/Documents\/Books\/Assembly%20Language%20Programming%20for%20the%20CoCo3%20%281987%29%20%28Laurence%20A%20Tepolt%29.pdf\" title=\"Tepolt\">Tepolt<\/a> has this wrong. So I decided to create a test program and accompanying video to document this first hand.<\/p>\n<p>Here is the <a href=\"https:\/\/www.macmess.org\/downloads\/PIA2Test.zip\">test<\/a> program.\n<a href=\"http:\/\/tlindner.macmess.org\/wp-content\/uploads\/2024\/02\/Capture.png\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/tlindner.macmess.org\/wp-content\/uploads\/2024\/02\/Capture.png\" alt=\"PIA Test Program\" width=\"642\" height=\"512\" class=\"alignnone size-full wp-image-1006\" \/><\/a>\nIt is a menu driven program that allows you to choose a specific mirror address for PIA 2, then allows you to choose one of three tests.<\/p>\n<p>Test &#8216;S&#8217; produces a square wave using the CoCo&#8217;s DAC. This DAC is connect to port A of the PIA.\nTest &#8216;B&#8217; produces a square wave using the CoCo 1 bit sound source. This is connected to bit 1 of port B of the PIA.\nTest &#8216;V&#8217; toggles the A\/G line of the VDG. This is connected to bit 7 of port B of the PIA.<\/p>\n<p>When using this program on a CoCo 3 you will find the the second PIA only responds from $FF20 to $FF2F. And the VDG test only responds to $FF20 to $FF23, because the GIME only see writes to these specific addresses.<\/p>\n<iframe loading=\"lazy\" width=\"560\" height=\"315\" src=\"https:\/\/www.youtube.com\/embed\/lvSHaDOJJPA?si=IlXvVWg6DP1QEEAv&amp;controls=0\" title=\"YouTube video player\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" allowfullscreen><\/iframe>","protected":false},"excerpt":{"rendered":"<p>The second PIA has a smaller mirror in the CoCo 3 than the CoCo 1\/2. It goes from $FF20 to $FF2F. The CoCo 1\/2 mirror is from $FF20 to $FF3F. Recently I was challenged to find a citation for this &hellip; <a href=\"https:\/\/tlindner.macmess.org\/?p=1005\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>","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-1005","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/tlindner.macmess.org\/index.php?rest_route=\/wp\/v2\/posts\/1005","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/tlindner.macmess.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/tlindner.macmess.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/tlindner.macmess.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/tlindner.macmess.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1005"}],"version-history":[{"count":4,"href":"https:\/\/tlindner.macmess.org\/index.php?rest_route=\/wp\/v2\/posts\/1005\/revisions"}],"predecessor-version":[{"id":1010,"href":"https:\/\/tlindner.macmess.org\/index.php?rest_route=\/wp\/v2\/posts\/1005\/revisions\/1010"}],"wp:attachment":[{"href":"https:\/\/tlindner.macmess.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1005"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/tlindner.macmess.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1005"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/tlindner.macmess.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1005"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}