Suspiciously similar to Hex, Pex is Brazeneck College's version of the super-computer machine, "invented" by Adrian Turnipseed, who received a professorship from Archchancellor Henry in the process. Pex uses chickens, instead of ants, to generate the "morphic resonation effect". It is far more efficient, as edible eggs are produced. Pex is also being constructed in a purpose-built room that Henry has named the "Higher Magic Energy Building", rather then scattered all over the High Energy Magic Building. At least, according to the Archchancellor of Brazeneck.
Henry will insist, if questioned, that Pex is completely different from Hex, and that any similarities are a result of his policy of "adopt, adapt, and improve". However, as Ridcully comments, the policy is much more like "grab, copy, and look innocent". In fact, Hex and Pex are so similar that Professor Turnipseed forgot to rebuild the morphic resonator to allow for the necessary changes in the blit/slood interface. This meant, that due to a blit devolution, Pex mutated into a seventy-foot chicken which rampaged around the city of Pseudopolis. It began laying eight to nine feet high calcium-shelled eggs very rapidly, and the senior wizards of Brazeneck proved unable to bring the situation under control, to Ridcully's great delight.
Of course, Ridcully graciously offered UU's assistance, and accompanied by Ponder Stibbons, the rest of the Faculty, and reporters from the Ankh-Morpork Times, made their way to resolve the matter, and add what Wizards prefer to call gravitas to the situation.
Pex may be inspired by the Google model. A web page from Google has described how their ranking algorithm is based on pigeons pecking (PigeonRank™). Page and Brin reasoned that low cost pigeon clusters (PCs) could be used to compute the relative value of web pages faster than human editors or machine-based algorithms. This April Fools joke appeared in 2002, some 7 years before the publication of Unseen Academicals.