[comp.sys.apple] Dual ROMs

forde@EGLIN-VAX.ARPA ("MAJ ERIC S. FORD") (05/27/87)

In an earlier posting Tak Ariga referred to programming the Apple ROMs, both
enhanced and un-enhanced, into 27128 EPROMs and using a toggle switch to
select whichever you want for a given application.  This mod has been 
discussed in Computer Shopper by Don Lancaster and in Understanding the Apple
IIe by Jim Sather as well as similar mods discussed in Computist magazine.
So far I have only made the Chargen mod on my system and it works just fine.
I would suggest to those making the full mod that you really want the monitor
ROM select and Chargen ROM select to be on separate toggle switches.  The 
reason being that you have to power down, or at least re-boot, when you cycle
the monitor ROMs since this code is being continually executed while the
computer is on.  The Chargen ROM can be switched at any time however.  I have
not found any significant software incompatibilities that require the presence
of both ROMs except for the Chargen - being able to deselect Mousetext is
essential for using Applewriter or the earlier version of MicroCookbook.

Eric S. Ford

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