!pr1
Two ROM Sets in One Apple //e..............Bob Sander-Cederlof

If and when you decide to upgrade to the new enhanced //e ROMs (which Apple sells for $70 along with a 65C02), you will probably have to turn your old ROMs over to the store that makes the switch.  Reportedly, Apple is binding the stores with a contract that forces them to collect all the old chips.

That is VERY unfortunate.  It could lead to wild shouting and panic, when you discover some of your favorite old software no longer works.

The upgrade consists of three parts:

!lm+8
!pp-3
*  the new processor chip (65C02), which is nice but not especially useful until software which uses its new features becomes available;

*  a new character generator ROM which includes special characters for icons and line drawing in text mode (called the "mouse" characters).

*  new CD and EF ROMs which upgrade the firmware.
!pp0
!lm-8

The new firmware does NOT use any of the new features in the 65C02, so you could use it without the new cpu chip.  Furthermore, there is no absolute requirement to have the new character generator installed.  The new firmware is much better than the old, having lost some bugs and speeded up the 80-column scrolling and added lower-case support to Applesoft (among other things).  It is compatible with the 6502, the 65C02, and the new 65802.

I personally do not yet have any use for the mouse characters, and do not expect to.  Don Lancaster, in the June 1985 issue of "Computer Shopper", tells how to connect a 2764 EPROM in the character generator socket.  The 2764 can hold two complete character sets, because it has twice the capacity of the 2732 normally in that socket.  However, the socket has only 24 holes and the 2764 has 28 pins!  Don shows how to wire this up with a socket adapter, and use a toggle switch to select either half.

And now Apple has "sort of" released an even more enhanced set of firmware, with debugging stuff built in.  You may not see them on the open market for some time, but I like them even better than the standard enhanced ROMs.  The "debug" ROMs add an absolute RESET (ctrl-RESET with solid apple), 16-byte hex display in the monitor when in 80-column mode, display of both hex and ASCII values of each byte in a memory dump, and the ability to use all monitor commands on both main and auxiliary memory.  The disassembler and miniassembler are both present, and enhanced to include the 65C02 extensions.

The CD and EF ROM sockets are compatible with 2764 EPROMs.  You can also use 27128s, which have twice the space.  Pin 26 on the 2764 is always tied to +5 volts.  On a 27128, pin 26 selects the top or bottom half of the 16K bytes inside.  You can burn one set of firmware in one half, and the other set in the other half.  Then bend out pin 26 a little, so that it does not go into the socket when you insert the chip.  Attach a clip lead to the bent-out pin, and connect the other end to either +5 volts or ground, to select the half you want at any given time.

You can connect it to a toggle switch, or just stick the bare end of a wire into the game paddle connector.  If you use the game socket on the motherboard, pin 1 is +5 volts and pin 8 is ground.  Or stick a wire into one of the annunciator outputs (pins 12, 13, 14, and 15) so you can flip back and forth between firmware sets by software control.

It can be a little tricky to make a copy of the ROM firmware and get it into RAM or on a disk, so that you can later burn it in your own EPROM.  Especially in the Cxxx part.  My approach, since I have more than one Apple, is to put my SCRG PromGramer card in a different machine.  Then one by one I can read the //e ROMs and burn them into the appropriate 27128s.  This a lot faster than trying to figure out how to flip all the //e soft switches so as to get at the different banks of Cx ROM code.

I have recently seen 27128s priced as low as $5 and as high as $20, in the back of Byte magazine.  It is well worth it to invest in a PromGramer, at $140, and an EPROM eraser ($50 to $100 from Logical Devices in Florida, see Byte ads).  You can keep your Apple standard for commercial software, and still have your own private firmware on the motherboard at the flip of a switch!
