{"id":2322,"date":"2019-07-20T23:26:27","date_gmt":"2019-07-20T23:26:27","guid":{"rendered":"http:\/\/www.sydneysmith.com\/wordpress\/?p=2322"},"modified":"2019-07-20T23:26:48","modified_gmt":"2019-07-20T23:26:48","slug":"hp-25-wait-loop","status":"publish","type":"post","link":"https:\/\/www.sydneysmith.com\/wordpress\/2322\/hp-25-wait-loop\/","title":{"rendered":"The HP-25 Wait Loop"},"content":{"rendered":"

The Wait Loop is what happens when your calculator is sitting on your desk and wondering what you’ll need next. This article covers that. <\/p>\n

The calculator is ON. The PRGM-RUN switch is in RUN. It’s waiting for you to press a key. This is the microcode sequence for that:
\n<\/p>\n

\r\nHP25 Logging started.\r\n\r\n; A= 0000ffffffffff B= 21000000000000 M1=20000000000202\r\n; S= ...3.5..........\r\n\r\nWaitLoop:\r\n00742 0 -> s 3\r\n00743 if 0 = s 3 then goto 01672\r\n00745 if 0 = s 15 then goto 00742\r\n\r\nWaitLoop:\r\n00742 ...\r\n<\/pre>\n
<\/code>
\ns3 is the RUN-PRGM switch. It is checking to see if we’ve decided to program the calculator instead. We haven’t. We’re still in RUN mode. s3 is 1.
\ns15 is key_pressed. If a key hasn’t been pressed, it goes back to the start of the loop.
\nIt keeps wondering.<\/p>\n
It’s pretty straight forward.<\/p>\n
By the way, you can also see ” 0.00″ in the display; given what is in the A and B register. B=2 blanks out the first digit (” “). B=1 lights up the decimal point after the second one (“0.”). B=0 after that shows the remaining digits. For the woodstock calculators (HP-21 to HP-29 and HP-67), an “f” in the A register shows as blank.<\/p>\n
This is part of the HP-25 topic<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"
The Wait Loop is what happens when your calculator is sitting on your desk and wondering what you’ll need next. This article covers that.<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[16,5,69],"tags":[],"_links":{"self":[{"href":"https:\/\/www.sydneysmith.com\/wordpress\/wp-json\/wp\/v2\/posts\/2322"}],"collection":[{"href":"https:\/\/www.sydneysmith.com\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.sydneysmith.com\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.sydneysmith.com\/wordpress\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.sydneysmith.com\/wordpress\/wp-json\/wp\/v2\/comments?post=2322"}],"version-history":[{"count":2,"href":"https:\/\/www.sydneysmith.com\/wordpress\/wp-json\/wp\/v2\/posts\/2322\/revisions"}],"predecessor-version":[{"id":2324,"href":"https:\/\/www.sydneysmith.com\/wordpress\/wp-json\/wp\/v2\/posts\/2322\/revisions\/2324"}],"wp:attachment":[{"href":"https:\/\/www.sydneysmith.com\/wordpress\/wp-json\/wp\/v2\/media?parent=2322"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.sydneysmith.com\/wordpress\/wp-json\/wp\/v2\/categories?post=2322"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.sydneysmith.com\/wordpress\/wp-json\/wp\/v2\/tags?post=2322"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}