Re: Info on Apple ][e enhancement

[edward@pro-ren.cts.com (Edward Floden)]

In <Pine.3.07.9409211950.A28342-c100000@acme.freenet.columbus.oh.us>
dalloff@freenet.columbus.oh.us (Dave Althoff) writes:

>There has been a lot of chatter about the difference between the 6502 and
>the 65C02, and changed opcodes, and new NOPs, and other stuff.
>
>I have seen precious little about the OTHER changes with the enhancement. 
>These are the changes which have PREVENTED me from getting the enhancement
>for my machine, and which cause nearly ALL of the compatibility problems
>(in my experience).

I solved that problem two months after I installed the enhanced ROMs into my
IIe.  I bought a PC board called the "Switchback", which allows me to use
either my old (pre-enhanced?) ROMs or the new enhanced ROMs.

The card is installed by first removing the selected ROMs from the logic
board.  Then, the card is plugged into the logic board, its having pins which
are then plugged into the empty ROM sockets.  Finally, both sets of ROMs are
plugged into sockets on the card.  To switch between the sets, you can use
the "old/new" switch on the card itself, or press an external button while
you're booting; the external button will allow you to boot up with the set of
ROMs that is not currently selected by the switch on the card.

Only the CPU is "permanently" replaced: you'll always have the 65C02
installed, and not the old 6502.  There's no disadvantages to that
configuration that I've even noticed.

In 1986 (a long time ago :), the card cost $25.