In article , android
wrote:


which got 16bit support with CC...

plug-ins did, however, photoshop itself had support for 16 bit since
1992 in version 2.5, enhanced with version 5 in 1998 and again in 2003
with cs. https://en.wikipedia.org/wiki/Adobe_Photoshop_version_history

Liar. From the link in the above: "16 bit per channel layers, painting,
and adjustment" were added in CS/PS8

scroll up to version 2.5, where it states "16 bit per channel support".