On 2 Mar 2004 at 13:11, Branko wrote: > > Note that this Coldfire generation can still _not_ offer full 68k > > compatibility, even _with_ the emulation library. The reason is, that > > some instructions with the same opcode as 68k, but different behaviour, > > can not be trapped. If I remember correctly from earlier considerations, > > this would not affect C68 generated code, but existing QL assembler > > software, including the operating systems. > > > > However this CPU allows to implement the QL operating system _interfaces_ > > without any changes. This is a major advantage to all other non-68k > > architectures, when native implementations are considered. > > > So, what does this mean ? Will there be a QL with that Coldfire ?
Personally, I no longer have plans in that direction, at least as long as the QL operating system situation doesn't improve drastically. Nevertheless this CPU has the best 68k compatibility of all Motorola CPUs (which are faster than the 68060) since many years. Just thought it deserves a mention. BTW aren't you a hardware designer, too? If so, you are among the persons to be asked :-) > What software will run on it unchanged, what will have to be > recompiled/rewritten/modified and what will probably have to be scrapped ? If we assume an operating system had been ported, and the (existing) emulation library for the missing 68k instructions works, SBASIC programs and compiled C68 programs could remain unchanged. Assembly language programs need to be reviewed wherever they use a "misbehaving-but-not- emulated" instruction. There are occasions where these instructions can remain unchanged, because the differences (e.g. in flag behaviour) are not actually exploited by the following instructions, and others, where a fix is necessary. An interesting thing about the CF 4e is: Assembly language programs could be written using a common instruction subset, so the same binary works on a real QL and the CF 4e. And: All operating system calls could remain unmodified, as well as the documentation of the operating system. All the best Peter
