Commodore CASSIOPEI, User Manual

Page: 70 / 76

12 Compatibility of the Cassiopei
The following paragraphs will describe the overall functionality of the Cassiopei, functionality that
is similar for all supported computer models.
Cassiopei fastloader
Some programs (and these are very rare) will not load using the Cassiopei fastloader. The reason
for this is that if the program that must be loaded needs uses the same memory space as the
Cassiopei's fastloader routines then the program that is loaded overwrites the fastloader program
and the loading simply stops. The only solution to this problem would be to load the program using
the “standard kernel loader” (a.k.a. the “slow” method of loading).
For the VIC-20, C64, C16/+4 the cassette buffer is also used for storing the fastloader code, these
computers do not require the use of the stack to store the fastloader code.
For the PET the fastloader stores itself into the cassettebuffer (Cassette buffer#1 and a small
portion of the stack). The Cassiopei uses a portion of the stack because the fastloader needs to be
stored somewhere and Cassettebuffer#2 would be a nice place BUT this is exactly what the earlier
programmers thought as well, so therefore cassette buffer #2 can not be used by the Cassiopei
fastloader code, fortunately the stack is large enough to store a part of the fastloader code. The
reason why the PET's fastloader is larger then the C64, VIC-20, C16/+4 fastloader code is simply
because the IO-lines are much easier to control on the non-PET computers and therefore requires
less code.
Jiffy-DOS
The Cassiopei is not compatible with JiffyDOS equipped computers. This because Jiffy-DOS
disables the use of the cassette and occupies the cassette buffer in memory. Therefore the Cassiopei
cannot function properly. A simple workaround would be to disable JiffyDOS or to load the
programs that require the use of the Cassiopei from disk.
Cartridges
The Cassiopei may function with various kind of cartridges, however cartridges that add
functionality in the form of speedloaders and BASIC extensions might cause problems as they
might occupy important memory locations (BASIC jump vectors). Regarding the “PRG slow
loading mode” (standard kernal loader) and the “.TAP file loading mode” there are no
incompatibilities to be expected (considering the .TAP and .PRG program itself is compatible with
the cartridge).
The Chameleon cartridge, on the C64, is a completely different story, this cartridge takes over the
C64's processor. And because the cassetteport is connected to the C64's processor the tape
functionality simply does no longer work!
Cassetteport related hardware
The Cassiopei should not be used in combination with other hardware connected to the
cassetteport. For instance, the 1541 ultimate tape adapter or a cassetteport splitter allowing to
connect more then 1 datasette to the cassetteport. This because the Cassiopei uses the IO-lines of
the cassetteport in a more advanced way then then all other existing hardware. When combining
other cassetteport hardware with the Cassiopei damage might occur.
2019-10-27 Page 70 of 76 CASSIOPEI v2.0