jdc@beach.cis.ufl.edu (Jeff Capehart) (05/05/88)
I have had some peculiar problems with programs working fine on a //e and not working on a //gs. The problem is that they will crash into the monitor on the GS with an address in the 00/Dxxx range. Since the programs are operating in compatibility mode, or rather they are *SUPPOSED* to operate in that mode, I am assuming that all the bank switching should work fine, and that the memory there will be RAM/ROM depending on the soft-switches. Some programs like to copy the ROMs to the RAM so that they can operate freely in the 16k Ram card area (language card ram) without having to switch around to access the monitor routines. I am curious if anyone else has had problems like this and if there is something fairly standard to check. An example of a solution might be something like.... on the //e you can double reference address $C011 and that sets the bank 1 on, but on the GS it will flip it out of compatibility mode... (Obviously this is wrong, but this is the kind of answer I am looking for... if there is one.) Thanks in advance... Apple2 shall live on! -- Jeff Capehart Internet: jdc@beach.cis.ufl.edu University of Florida UUCP: ..!ihnp4!codas!uflorida!beach.cis.ufl.edu!jdc
KAPFFER@DMZRZU71.BITNET (Matthias Kapffer) (05/12/88)
Jeff,
the Apple IIgs has no real compatiblity mode (like GO64 on a C= 128) but just
a lot of single options like shadowing of video buffers (but not text page
2... ) and the I/O area, emulation vs native mode of the 65816 (don't mix
this up with Apple //e - Apple IIgs compatiblity !), CPU speed etc. All of
the advanced features of a IIgs can be used by programs running in
"emulation".
To come down to your specific problem, the hardware of the "language card"
doesn't cause any troubles, but the monitor activly manages the state of the
banked switched RAM in this area to offer unlimited access to it (the
appropriate ROMs can be read in bank $FF anyway). This causes some EXEC files
to crash which use monitor commands to switch over to the RAM and load some
files into it. Also "G" commands will always call the ROM in this address
range.
Matthias Kapffer
<KAPFFER@DMZRZU71.BITNET>