USB to ps2


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its always puzzled me that you can plug a USB keyboard into a ps2 connector, do all keyboards have a legacy mode? can this be relied on in future?

can I just plug in the d+ and d- and treat them as ps2 data and clock? and just make my own ps2 interface circuit?

getting a ps2 keyboard is like getting hens teeth from a snow hen in the Caribbean now a days...

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sorry link on my tablet couldn't get the actual link but that should get you the PDF...

page 10 mentions a pull down resistor on USB hubs and ps2 mode...

lets hope keyboard manufacturers keep legacy PS/2 mode alike!

will research more!

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In a previous job I worked in the hardware group at a large tech company, some of which included mice and keyboards. This was during the PS/2 to USB transition period in the early 2000's and our devices had a legacy mode built into the ASICs embedded in them. The PS/2 to USB adapters were passive and would only work with keyboards and mice that had dual modes. We also had mice that could connect to PS/2 or serial the same way.


I just had a look on ebay and there are dozens of PS/2 keyboards listed. Amazon has loads of them too. You might also try a thrift store or computer recycling center, I still see PS/2 types frequently.

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