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Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ucbvax!cdfb.utoronto!cssu
From: cssu@cdfb.utoronto.UUCP
Newsgroups: comp.sys.apple
Subject: Re:  3.5 inch drives
Message-ID: <8705270122.AA24022@cdfb.toronto.edu>
Date: Tue, 26-May-87 21:22:32 EDT
Article-I.D.: cdfb.8705270122.AA24022
Posted: Tue May 26 21:22:32 1987
Date-Received: Thu, 28-May-87 06:46:18 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: world
Organization: The ARPA Internet
Lines: 35

>
> Finally, since I am considering enhancing my IIe (I want the 65C02, I
> don't want the chargen ROM, and I need the two monitor ROMs), does
> anyone know of any programs that will break if I enhance?  Can I install
> the 65C02 and the two monitor ROMs and keep my old chargen ROM?  What
> do I give up by enhancing?  I know that I lose the self tests - anything
> else?
>

There is a neat trick to have the best of both worlds at the flick
of a switch.  The //e ROMs are 64K, and I think the Char Gen is the
same.  To have both the enhanced and the unenhanced //e, what you do
is to burn your own EPROMS.

I have a friend who did this trick...  He burned the unenhanced //e
ROMS in the lower 64K of a 128K EPROM (27128), and the enhanced //e
ROMS in the upper 64K.  He then put a toggle switch to change the
high bit to select either the lower or the upper half of the 27128.
Apparently the pinouts for a 2764 (what the Apple //e ROMS are, I believe),
and the 27128 are very similar.  So, at the flick of a switch, you can
switch between an enhanced and an unenhanced //e.

The Char Gen had the same trick.  The difference there is that one have
Inverse characters, the enhanced has Mousetext characters...
He rigged the switch so that both ROMs are switched at once...

--Tak

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