 The 65C02 added more CPU instructions, the new character ROM added 32 special "MouseText" characters (which allowed the creation of a GUI-like display in text mode, similar to IBM code page 437), and the new ROM firmware fixed problems and speed issues with 80-column text, introduced the ability to use lowercase in Applesoft BASIC and Monitor, and contained some other smaller improvements (and fixes) in the latter two (including the return of the Mini-Assembler—which had vanished with the introduction of the II Plus firmware).Although it affected compatibility with a small number of software titles (particularly those that did not follow Apple programming guidelines and rules, used illegal opcodes that were no longer available in the new CPU, or used the alternate 80-column character set that MouseText now occupied) a fair bit of newer software — mostly productivity applications and utilities — required the Enhanced chipset to run at all.An official upgrade kit, consisting of the four replacement chips and an "Enhanced" sticker badge, was made available for purchase to owners of the original Apple IIe.