>I think there may be some minor Z380 incompatibilities with Z80.
>I got a faq about the Z180 in which are mentioned the following
>differences between Z180 and Z80 and since Z380 is probably more like
>Z180....
I wouldn't be too sure about that!
>"For DAA (Decimal adjust), if you execute this instruction after DEC
>instruction (especially DEC instruction on 00h, then execute DAA), Z180
>results in F9h while Z80 results in 99h. It is because the Z80 CPU
>refers "Internal Carry flag" while Z180 doesn't.
F9h would be false, it's a BUG in the Z180 (or errata ;) and I'm pretty
sure the Z380 acts correctly, like the Z80 does.
>For RLD/RRD (Rotate Left/Right Digit), Z180's flag will reflect the
>contents of the memory location pointed by HL register, while Z80
>reflects the contents of the Accumulator.
That's interesting, but I don't think ANY programmer EVER made a program
depend on the Z/S flags after RLD/RRD. No Z80 documentation AFAIK even
states whether the contents of A or (HL) affect the flags!
>But, there are very few applications which use DAA instructions after
>DEC and use flag after RLD/RRD instructions."
Exactly.
DAA'ing after DEC can be pretty useful though, but since the Z180's
behaviour in this is WRONG I think they've corrected that in Z380.
Greetz,
Patriek
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