{"id":1312,"date":"2018-06-03T07:45:40","date_gmt":"2018-06-03T06:45:40","guid":{"rendered":"http:\/\/www.randomorbit.co.uk\/?p=1312"},"modified":"2018-06-07T21:30:01","modified_gmt":"2018-06-07T20:30:01","slug":"dec-pdt-11-150-part-2","status":"publish","type":"post","link":"https:\/\/www.randomorbit.co.uk\/?p=1312","title":{"rendered":"DEC PDT-11\/150 – Part 2."},"content":{"rendered":"

In the last post<\/a> I described the PDT-11\/150 a little bit and the state of play. It was showing signs of life but not talking to me.<\/p>\n

It turns out the cable wasn’t right. Switch to a new cable, fire up GtkTerm<\/a> and we’re on the right lines.<\/p>\n

\"\"<\/a>What we have here is the ODT display. It doesn’t look much but it shows us that the machine is alive and conscious.<\/p>\n

Main switch settings.<\/h2>\n

There is a five switch DIL pack on the top board that sets various options for the machine. The manual gives the following explanations:-<\/p>\n

\"\"<\/a>IT seems a little odd that the switch labelled “Auto Baud” should be set to off<\/strong> to turn Auto Baud on<\/strong>. Really? Ah well.<\/p>\n

Mine are set as follows:-<\/p>\n

    \n
  1. ON – Auto Baud is disabled. Baud rate is set to 9600.<\/li>\n
  2. ON – Line clock is disabled.<\/li>\n
  3. OFF – Enable the DRAM refresh.<\/li>\n
  4. OFF – Disable the test mode.<\/li>\n
  5. OFF – Disable manufacturer mode.<\/li>\n<\/ol>\n

    Setting the switches this way I can get to the prompt you see above.<\/p>\n

    I have tried getting into the test mode but it doesn’t seem to work on my machine. I wondered if the self test at power up is failing and dropping me into the ODT but the error light on the front goes out so I guess not.<\/p>\n

    I haven’t turned on the line clock as I don’t know yet if I need an interrupt handler for it. Clearly we need DRAM refresh and fixing the Baud rate at 9600 is just A Good Thing (TM).<\/p>\n

    Booting?<\/h2>\n

    Now here’s a thing. I can’t find any information about how to get this thing to read a floppy. The manual describes setting the switches to get test mode. It says how to insert a floppy and how to handle them safely but nothing on how to boot the machine.<\/p>\n

    I’ve looked at both the technical manual and user guide (thanks to Bitsavers) but there is nothing.<\/p>\n

    A little test.<\/h2>\n

    Although I can’t boot from floppy, I can fire in code using the terminal and things are starting to look brighter.<\/p>\n

    Here is an example from the ODT<\/a> page on wikipedia<\/a>.<\/p>\n

    \"\"<\/a>This fires the letter ‘A’ at the console port as fast as it can and only stops when you press the reset switch.<\/p>\n

    Tada!<\/p>\n

     <\/p>\n

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

    In the last post I described the PDT-11\/150 a little bit and the state of play. It was showing signs of life but not talking to me. It turns out the cable wasn’t right. Switch to a new cable, fire up GtkTerm and we’re on the right lines. What we have here is the ODT … Continue reading DEC PDT-11\/150 – Part 2.<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_coblocks_attr":"","_coblocks_dimensions":"","_coblocks_responsive_height":"","_coblocks_accordion_ie_support":"","footnotes":""},"categories":[47,114,133,33],"tags":[],"class_list":["post-1312","post","type-post","status-publish","format-standard","hentry","category-c93-blog-posts","category-digital-equipment-corporation","category-pdt-11-150","category-c84-retro-tech"],"featured_image_src":null,"author_info":{"display_name":"andy","author_link":"https:\/\/www.randomorbit.co.uk\/?author=1"},"_links":{"self":[{"href":"https:\/\/www.randomorbit.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/1312","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.randomorbit.co.uk\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.randomorbit.co.uk\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.randomorbit.co.uk\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.randomorbit.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1312"}],"version-history":[{"count":3,"href":"https:\/\/www.randomorbit.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/1312\/revisions"}],"predecessor-version":[{"id":1320,"href":"https:\/\/www.randomorbit.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/1312\/revisions\/1320"}],"wp:attachment":[{"href":"https:\/\/www.randomorbit.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1312"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.randomorbit.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1312"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.randomorbit.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1312"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}