Re: Question about upgrading Apple IIe

[heuser.marcus@freenet.de]

> I have a German Apple IIe unenhanced.
> I wonder if I can change the CPU with a 65C02 and burn new roms (or eproms) with new enhanced firmware.

With a fitting set of ROMs this should be no problem.
The 65C02 is pin-compatible - but make sure, that it really is a 65C02
(or "6503" by Rockwell) and not a 65SC02, as its a bit different!

> What about German characters? Do I loose them if I change the three roms?

Could happen if you install the wrong "VIDEO ROM" (sometimes also
called "CHARGEN"). You need a German ROM if you want to display German
characters.

The other two ROMs are AFAIK no problem.

> Are there any incompatibilities with old software running on Dos 3.3 if I
> make the Apple enhanced?

The normal 6502 does allow for some "illegal" opcodes which were used
in some *seldom* cases. On any later variant (65C02, 65SC02, 65802 and
65816) these programs wouldn't work correctly because these CPUs have
opcodes with other functions instead.

There has also been some ROM trickery (using inofficial entry jumps) -
but this is also very uncommon, imho.

You definitely should go for the upgrade - you can actually use more
programs, than you will encounter problems with - additionally the CPU
runs cooler and will perhaps last longer.