Programmable Interval Timer: Difference between revisions
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The reload value can be changed at any time, however the new value will not affect the current count until the current count is reloaded (on the next rising edge of the gate input). When this occurs counting will continue using the new reload value. |
The reload value can be changed at any time, however the new value will not affect the current count until the current count is reloaded (on the next rising edge of the gate input). When this occurs counting will continue using the new reload value. |
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=== Warning!!! === |
=== Warning!!! === |
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The PIT isn't emulated properly on QEMU/VirtualBox. Use real machines or Bochs to test it (if you delay function works well on QEMU this doesn't mean it will work on a real machine). There is also a piece of bad PIT code in books, so look out!!! |
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On modern PCs the most of this big mess of modes may be unimplemented at all. I thought I had found a bug in Bochs, when a delay routne (copied from a book) didn't worked (On QEMU and VirtualBox the code worked well). But this code also failed on my notebook, so it's better to not use any non-standart tricks. Enjoy mode 2. |
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== Counter Latch Command == |
== Counter Latch Command == |
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