Re: Apple //e Upgrade Failed?

[dempson@actrix.gen.nz (David Empson)]

Bryan Parkoff <none@nospam.net> wrote:

>     I have unenhanced Apple //e.  The model is A2S2064.  The serial number
> is 1A2S2-D44 0HDK A2S2064.  I replaced from original video ROM chip to new
> one which it includes MouseText, but it is still in unenhanced Apple //e.
> It is working fine.
>     I tried to swap from 6502 CPU to 65C02 CPU while CD-EF ROM chips are
> still unenhanced Apple //e, but it failed to work.  The screen is black
> nothing.  Also, I tried another 65C02 CPU from Zip Chip to be installed.  It
> did not work and the screen is still black.  It works fine on Apple II+.

The unenhanced IIe ROMs should work with either type of CPU.

Given the evidence, and assuming the CPUs were inserted correctly, I'd
be inclined to suspect some kind of fault with that IIe which only
affects a 65C02.

Was the first 65C02 known to work in an Apple IIe?  Some 65C02s don't
work in a II+, but the IIe is more forgiving.  The main requirement is
that it must be rated at 2 MHz or faster in order to meet the timing
requirements.

>     Do you have a clue what it is causing?  If I get it working correctly, I
> will swap CD-EF ROM later to be enhanced Apple //e.

Incidentally, you can use the enhanced IIe ROMs with a 6502 CPU.  The
ROMs don't contain any 65C02 instructions.

This isn't a good idea as a long term setup, because some software might
recognise the enhanced firmware and assume that it is OK to use 65C02
instructions because you presumably have an enhanced IIe.

Software that wants to play it safe will detect the type of CPU
directly, ignoring the firmware.

-- 
David Empson
dempson@actrix.gen.nz