Re: Proterm and the //E

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

In article <31D445BE.6B42@mail.gpbx.net>,
Jack Countryman  <jcoun00@mail.gpbx.net> wrote:
> > 
> > Would anyone happen to know, then, how to tell an enhanced //e from
> > a mere //e with a 65c02, from software?
> > 
> > Tilghman
> Yeah...the enhanced ones say Apple //E at the bottom of the screen when 
> they start up....the old ones say Apple ][ E....that at least identifies 
> the ROM chip (65C02 versus 6502).  

You have some terms mixed up.  The "ROM" is the pair of chips that
contain the monitor, text I/O firmware and Applesoft BASIC.  The
"65C02" or "6502" is the CPU.

In answer to the various questions on this thread (and anticipating a
few more):

1. A IIe cannot truly be termed "enhanced" unless all four chips have
   been replaced (the CPU, CD ROM, EF ROM and video ROM).  You definitely
   need to replace the CPU and main ROMs for software to reliably work as
   if it is fully enhanced, but you will get display problems with programs
   that try to use MouseText unless you also replace the video ROM.

   (There is a useful option for international IIe's: it is possible
   to burn your own video ROM which contains the original and enhanced IIe
   character sets, and the switch on the underside of the keyboard can be
   used to toggle between them.)

2. Some programs will work if you just replace the CPU with a 65C02, but
   other programs might look at the ROMs to work out if you have an enhanced
   IIe, and refuse to run if the old ROMs are present.

3. It is possible to replace the ROMs with the ones from the enhanced
   set and leave the original 6502 CPU installed, but I definitely wouldn't
   recommend doing this, as it will confuse some software.

4. Software is not able to detect which video ROM is installed in a
   IIe, except by displaying something on the screen and asking the
   user what they see.

5. It is possible to detect the 65C02 without relying on the ROMs, and I've
   posted a machine language routine to do this (a couple of years
   ago, reposted at least once).  I got the original routine from
   "Programming the 65816, et. al." by Eyes & Lichty, and modified it
   to make it more reliable and to be able to detect a Rockwell R65C02
   (which has more instructions than the standard 65C02, but the extra
   instructions are not compatible with the 65802 or 65816).  The
   routine can detect a 6502, 65C02, R65C02 or 65802/65816.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand