Originally Posted by AV Doogie
I do not believe all previous cables used all of the pins and functionality of the 19 pins available.
On this, really the only issue is that Ethernet pair you mentioned; otherwise, all HDMI cables of all versions should be structurally identical inside.
However, I have heard rumors now and then that in the early days of HDMI there were some cable manufacturers who put 18-conductor stock in their HDMI cables, leaving out the connection on the one pin that was reserved for future use. Such a cable would never have passed HDMI testing, which has always required that all conductors be present, but of course it's possible someone might have made such cables unbeknownst to HDMI Licensing, and because the conductor was not used they would have worked fine (and would still be working fine). As I say, these are rumors--I haven't ever yet seen an actual 18-wire HDMI cable stock, but it certainly might have been done by somebody looking to save a bit.
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