Which HP calculator had "The New Accuracy" first?

[rprosperi]

It's possible that the code really was originally developed for the HP-91 (the first TopCat), and then it was also used for the HP-22 (both use Woodstock technology), which was likely much quicker to market.

The 91 was the first machine in a totally new line with many innovations such as case, layout and keyboard design, thermal printer, adding ENG notation, etc. while the HP-22 was just another Woodstock which had been out for many months already, so not unreasonable that they wrote it for the 91, copied it in the 22 and the 22 simply were produced 6 months earlier. Just speculation, but it does explain the observed facts and stories.