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From: nparker@cie-2.uoregon.edu (Neil Parker)
Newsgroups: comp.sys.apple2.programmer
Subject: Re: Enhanced IIe question
Date: 12 Mar 1997 07:42:46 GMT
Organization: University of Oregon Campus Information Exchange
Lines: 58
Message-ID: <5g5mpm$ncu@pith.uoregon.edu>
References: <3324DA31.4407@hutchnet.hk>
NNTP-Posting-Host: cie-2.uoregon.edu
NNTP-Posting-User: nparker

In article <3324DA31.4407@hutchnet.hk> ivanc@hutchnet.hk writes:
>Is there a way to check whether my apple IIe is enhanced or not through
>programming code?

Yes.  You need look at the ID bytes in the ROM.  PEEK(64448) returns 234 on
an unenhanced IIe, and 224 on an enhanced IIe.

This is actually part of a longer test, which goes something like this:

If PEEK(64435) = 56, then you're on an original Apple II.
If PEEK(64435) = 234, then you're on an Apple II+ (or III in emulation mode).
If PEEK(64435) = 6, then you're on a IIe, IIc, or IIGS.  In this case...
     If PEEK(64448) = 234, then you're on an unenhanced IIe.
     If PEEK(64448) = 224, then you're on an enhanced IIe or IIGS.
     If PEEK(64448) = 0, then you're on a IIc.  In this case...
          PEEK(64447) is the IIc version byte.  The values 255, 0, 3, and 4
          indicate (respectively) the first four IIC versions.  The value 5
          indicates a IIc+.

Distinguishing between an enhanced IIe and a IIGS requires machine language:

        SEC
        JSR $FE1F
        BCC IIGS
NOTGS   ...

Note that the IIe enhancement kit consists of three parts--the enhanced ROM,
the 65C02 processor, and the Mousetext character generator.  These parts
are usually installed together, but some people don't upgrade all three
chips (usually because they use one of the handful of older programs that's
illegible on a Mousetext-equipped machine).  So it may be useful to test
for the enhancement components separately.

The above test tells you whether or not you're using an enhanced ROM.

Distinguishing between the (unenhanced) 6502 and the (enhanced) 65C02 is
possible with a little machine language:

     LDA #$99
     CLC
     SED
     ADC #1
     CLD
     BEQ ENHANCED

This works by checking for a hardware bug in the original 6502...when
adding in decimal mode, it sets the zero flag before it decimal-adjusts
the result.

As far as I know, there's no way to for a program to test whether or not
the Mousetext character generator is installed.

               - Neil Parker
-- 
Neil Parker, nparker@{cie-2,cie}.uoregon.edu, http://cie-2.uoregon.edu/~nparker
     "I was going to be a neo-deconstructivist but Mom wouldn't let me."
                                     -- Calvin and Hobbes, 7/13/1995
Unsolicited commercial e-mail to my address will be discarded unread.