so it explains why I can't find the Holtek compiler on their site. It's pity - the C compiler for Holtek I used was quite good and efficient. In fact if you can find some copy of this compiler you can adjust it to the new controllers - in most of the cases you need only to change some definition tables - the instruction set is practically the same. Several years ago our company needed such compiler and I contacted and convinced HiTech to start making Holtek compiler, they did the job in few months because it's very similar to PIC compiler.
Writing assembler code is quite unefficient - it takes much longer, the code is unstable and not portable. Is the HOLTEK IDE compiler (payfree) not working for the new parts?