Editing Apple IIe (section)

===Enhanced IIe===
In March 1985, the company replaced the original machine with a new revision called the Enhanced IIe. It is completely identical to the previous machine except for four chips changed on the motherboard (and a small "''Enhanced''" or "''65C02''" sticker placed over the keyboard power indicator). The purpose of the update was to make the Apple IIe more compatible with the Apple IIc (released the previous year) and, to a smaller degree, the Apple II Plus. This change involved a new processor, the CMOS-based [[WDC 65C02|65C02]] CPU, a new character ROM for the text modes, and two new ROM firmware chips. The 65C02 added more CPU instructions, the new character ROM added 32 special "[[MouseText]]" characters (which allowed the creation of a [[Graphical user interface|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 [[Apple II Mini-Assembler|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 opcode]]s that were no longer available in the new CMOS-based CPU, or used the alternate 80-column character set that MouseText now occupied) a fair bit of newer software&nbsp;— mostly productivity applications and utilities&nbsp;— 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. An alternative at the time, which some users chose as a cost-cutting measure, was to simply purchase their own 65C02 CPU and create (unlicensed and illegal) duplicates of the updated ROMs using re-rewritable [[EPROM]] chips. When Apple phased out the Enhancement kit in the early 1990s, this became the only available method for users looking to upgrade their IIe, and remains so right up until the present day. An Enhanced machine identifies itself with the name "Apple //e" on its start-up splash screen (as opposed to the less-specific "Apple ][").