{"action":"created","issue":{"url":"https://api.github.com/repos/mattgodbolt/jsbeeb/issues/115","repository_url":"https://api.github.com/repos/mattgodbolt/jsbeeb","labels_url":"https://api.github.com/repos/mattgodbolt/jsbeeb/issues/115/labels{/name}","comments_url":"https://api.github.com/repos/mattgodbolt/jsbeeb/issues/115/comments","events_url":"https://api.github.com/repos/mattgodbolt/jsbeeb/issues/115/events","html_url":"https://github.com/mattgodbolt/jsbeeb/issues/115","id":165405100,"number":115,"title":"Master 128 model seems to run a bit fast","user":{"login":"BigEd","id":110176,"avatar_url":"https://avatars.githubusercontent.com/u/110176?v=3","gravatar_id":"","url":"https://api.github.com/users/BigEd","html_url":"https://github.com/BigEd","followers_url":"https://api.github.com/users/BigEd/followers","following_url":"https://api.github.com/users/BigEd/following{/other_user}","gists_url":"https://api.github.com/users/BigEd/gists{/gist_id}","starred_url":"https://api.github.com/users/BigEd/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/BigEd/subscriptions","organizations_url":"https://api.github.com/users/BigEd/orgs","repos_url":"https://api.github.com/users/BigEd/repos","events_url":"https://api.github.com/users/BigEd/events{/privacy}","received_events_url":"https://api.github.com/users/BigEd/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/mattgodbolt/jsbeeb/labels/bbc-master","name":"bbc-master","color":"bfd4f2"},{"url":"https://api.github.com/repos/mattgodbolt/jsbeeb/labels/timing","name":"timing","color":"fad8c7"}],"state":"open","locked":false,"assignee":{"login":"mattgodbolt","id":633973,"avatar_url":"https://avatars.githubusercontent.com/u/633973?v=3","gravatar_id":"","url":"https://api.github.com/users/mattgodbolt","html_url":"https://github.com/mattgodbolt","followers_url":"https://api.github.com/users/mattgodbolt/followers","following_url":"https://api.github.com/users/mattgodbolt/following{/other_user}","gists_url":"https://api.github.com/users/mattgodbolt/gists{/gist_id}","starred_url":"https://api.github.com/users/mattgodbolt/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/mattgodbolt/subscriptions","organizations_url":"https://api.github.com/users/mattgodbolt/orgs","repos_url":"https://api.github.com/users/mattgodbolt/repos","events_url":"https://api.github.com/users/mattgodbolt/events{/privacy}","received_events_url":"https://api.github.com/users/mattgodbolt/received_events","type":"User","site_admin":false},"assignees":[{"login":"mattgodbolt","id":633973,"avatar_url":"https://avatars.githubusercontent.com/u/633973?v=3","gravatar_id":"","url":"https://api.github.com/users/mattgodbolt","html_url":"https://github.com/mattgodbolt","followers_url":"https://api.github.com/users/mattgodbolt/followers","following_url":"https://api.github.com/users/mattgodbolt/following{/other_user}","gists_url":"https://api.github.com/users/mattgodbolt/gists{/gist_id}","starred_url":"https://api.github.com/users/mattgodbolt/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/mattgodbolt/subscriptions","organizations_url":"https://api.github.com/users/mattgodbolt/orgs","repos_url":"https://api.github.com/users/mattgodbolt/repos","events_url":"https://api.github.com/users/mattgodbolt/events{/privacy}","received_events_url":"https://api.github.com/users/mattgodbolt/received_events","type":"User","site_admin":false}],"milestone":null,"comments":25,"created_at":"2016-07-13T19:45:09Z","updated_at":"2016-07-20T15:17:18Z","closed_at":null,"body":"Running from the pi.ssd pi calculation program, version 12, at\r\nhttp://litwr2.atspace.eu/pi/pi-spigot-benchmark.html\r\nI'm getting timings from JSBeeb which are somewhat faster than a real Master.\r\nOn my Master, for 1000 digits it reports 176.23\r\nOn JSBeeb it reports 158.74 or 158.75\r\n\r\nMore conveniently, computing 80 digits takes 1.18 on my Master, 1.07 on JSBeeb\r\n\r\nI've attached v12 of the program - binary only - see the website for sources.\r\n[pi.ssd.gz](https://github.com/mattgodbolt/jsbeeb/files/362321/pi.ssd.gz)\r\n\r\nSee also the discussion at http://stardot.org.uk/forums/viewtopic.php?f=2&t=11458\r\n"},"comment":{"url":"https://api.github.com/repos/mattgodbolt/jsbeeb/issues/comments/233981882","html_url":"https://github.com/mattgodbolt/jsbeeb/issues/115#issuecomment-233981882","issue_url":"https://api.github.com/repos/mattgodbolt/jsbeeb/issues/115","id":233981882,"user":{"login":"BigEd","id":110176,"avatar_url":"https://avatars.githubusercontent.com/u/110176?v=3","gravatar_id":"","url":"https://api.github.com/users/BigEd","html_url":"https://github.com/BigEd","followers_url":"https://api.github.com/users/BigEd/followers","following_url":"https://api.github.com/users/BigEd/following{/other_user}","gists_url":"https://api.github.com/users/BigEd/gists{/gist_id}","starred_url":"https://api.github.com/users/BigEd/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/BigEd/subscriptions","organizations_url":"https://api.github.com/users/BigEd/orgs","repos_url":"https://api.github.com/users/BigEd/repos","events_url":"https://api.github.com/users/BigEd/events{/privacy}","received_events_url":"https://api.github.com/users/BigEd/received_events","type":"User","site_admin":false},"created_at":"2016-07-20T15:17:18Z","updated_at":"2016-07-20T15:17:18Z","body":"OK, see attached. It's probably worth revisiting this idea: initialise the timer to get into a known state, set up an ISR to catch the PC next time the interrupt fires, then run some code. Compare JSBeeb and a physical machine, see if the PC ever differs between the two. If it does, change the initial timer value a binary search to narrow down the first mis-timed interrupt. Then scratch your head.\r\n\r\nIn the ssd, you'll find some EXECable sources:\r\nPIT - a version of the BASIC wrapper which has such a gadget. It's initialising to &0800, but the binary search converged on the first fail at &07C1\r\ntest2 - simple single-instruction timer\r\nTIM1 - timing a composite of the RMW instructions\r\n[pi-mod.ssd.gz](https://github.com/mattgodbolt/jsbeeb/files/374032/pi-mod.ssd.gz)\r\n"}}
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