Today I got an Apple Enhanced IIe ROM Upgrade Kit from USA - fresh out of the box  Let us do an upgrade on my good old Apple IIe. An official upgrade kit, consisting of 4 replacement chips and an "Enhanced" sticker badge, was made available for purchase to owners of the original Apple IIe. When you start your computer, the unenhanced IIe displays "Apple ][" at the top of screen; the Enhanced IIe displays "Apple //e".
In March 1985 Apple introduced the Enhanced IIe. It was identical in every aspect to the original IIe, the only difference being four socketed chips had been changed on the motherboard: 6502, CD and EF ROMs, and the Video ROM. The 65C02 CPU added more instruction sets, the new ROM firmware fixed bugs and improved Applesoft BASIC, Monitor and 80 column routines, and finally the new Video ROM added "MouseText" characters first introduced in the IIc. Essentially the Enhancement was to make the IIe more compatible with the Apple II+ and IIc models. The original IIe (including the revision A board) could be easily user upgraded by simply swapping the 4 chips: CPU 65C02, Video ROM includes MouseText, and new
Monitor/Applesoft ROMs. Some places used to sell a IIe Enhancement kit
for $20.00.
The Apple IIe Enhanced Kit, produced in March 1985
A IIe Enhancement Kit does not include any extra RAM. You can expand a 64k
IIe to the standard 128k required for a fully Enhanced IIe via an Extended
80-column card. It plugs into the Aux Connector on the motherboard.
The Kit involved changes to make the IIe more closely compatible with The Apple IIc and II Plus. The upgrade kit (for previous IIe owners) consisted of four chips that were swapped in the motherboard: The 65c02 processor, with more assembly language opcodes, replaced the 6502; two more chips with Applesoft and Monitor ROM changes; and the fourth a character generator ROM that included graphics characters (first introduced on the IIc) called "MouseText".
The ROMs, Keyboard-Sticker, Manual and Packlist
The Enhanced IIe ROM changes fixed most of the known problems with the IIe 80-column firmware, and made it possible to enter Applesoft and Monitor commands in lower-case. The older 80-column routines were slower than most software developers wanted, they disabled interrupts for too long a time, and there were problems in making Applesoft work properly with the 80-column routines. These problems were solved with the newer ROMs.
The replacement ROM modules - enhanced CPU 65C02, Video ROM includes MouseText, and new
Monitor/Applesoft ROMs.
Except for being able to type and display lower-case characters, the
unenhanced IIe is very similar to the II+. A 128k Enhanced IIe adds a number of
features including 80-column firmware and 16-color double-lores and
double-hires display capability.
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 ANSI), and the new ROM firmware fixed problems and speed issues with 80 columns 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). The new MouseText characters caused a problem for some older programs at first, until they were upgraded; characters previously displayed as inverse upper-case would sometimes display as MouseText instead.
Monitor changes also included a return of the mini-assembler, absent since the days of Integer BASIC. It was activated by entering a "!" command in the Monitor, instead of a jump to a memory location as in the older Apple II. Also added were an "S" command was added to make it possible to search memory for a byte sequence, and the ability to enter ASCII characters directly into memory. However, the "L" command to disassemble 6502 code still did not handle the new 65c02 opcodes as did the IIc disassembler. Interrupt handling was also improved.
Information sources:
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Apple IIe Enhanced ROM Upgrade
