HP customers are showing frustration online as the vendor continues to use firmware updates to discourage or, as users report, outright block the use of non-HP-brand ink cartridges in HP printers. Dynamic security strikes againAfter paying up, it seems HP is set on continuing to use DRM to discourage its printer customers from spending ink and toner money outside of the HP family. The 6978's product page similarly states that the printer is meant for cartridges with "a new or reused HP chip, and it uses dynamic security measures to block cartridges using a non-HP chip