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@@ -16,7 +16,6 @@ http://ed-thelen.org/comp-hist/IBM-ProdAnn/4700.pdf |
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4704 Keyboard Protocol |
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====================== |
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On powering up the keyboard sends keyboard id; A3h for 6019284(62-key), for example. |
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@@ -24,6 +23,22 @@ After that firmware enters FC command mode and waits for parameter data from hos |
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so that it doesn't send any scancode until you send 'FF'(End of FC command). |
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Connector |
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--------- |
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Keyboard Plug from front |
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DSUB-9 |
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------------- |
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\ N 2 3 4 5 / |
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\ N N N N / |
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--------- |
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2 GND |
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3 VCC 5V |
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4 DATA |
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5 CLOCK |
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N No connection/No pin. |
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Keyboard to Host |
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---------------- |
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Data bits are LSB first and Pairty is odd. Clock has around 60us high and 30us low part. |
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@@ -40,7 +55,6 @@ Timing: Host reads bit while Clock is hi. |
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Stop bit: Keyboard pulls down Data line to lo after 9th clock. |
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Host to Keyboard |
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---------------- |
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Data bits are LSB first and Pairty is odd. Clock has around 60us high and 30us low part. |
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@@ -60,7 +74,6 @@ Timing: After Request keyboard pull up Data and down Clock line to low for s |
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Stop bit: Host releases or pulls up Data line to hi after 9th clock and waits for keybaord pull down the line to lo. |
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Scancodes |
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--------- |
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Keyboard doesn't send Break code for all keys except for Alt by default. |