>>In native mode the Z380 is compatible with the Z80. It can only execute
>>code in the first 64K of memory. Using a trick you can access data anywhere
>>in memory, but in the default configuration this is also restricted to the
>>first 64K.
>
>Not 100% true, even in native mode the Z380 ALU still 32 bits and by the
>way some coding tricks like:
>
>imagine you have to countdown the time of a game or what ever you want
>
> LD DE,(TimeCounter)
> LD HL,-2
> ADD HL,DE
>this wont give the good result on Z380
You are wrong. In native mode all calculations are done modulo 65536.
Otherwise Z380 could never claim Z80 compatibility!
>From the manual:
"The Z380 CPU can operate in either Native or Extended
mode, as controlled by a bit in the Select Register (SR).
In Native mode (the Reset configuration), all address
manipulations are performed modulo 65536 (16 bits). In
this mode the Program Counter (PC) only increments
across 16 bits, all address manipulation instructions (increment,
decrement, add, subtract, indexed, stack relative,
and PC relative) only operate on 16 bits, and the Stack
Pointer (SP) only increments and decrements across
16 bits."
ADD HL,DE works on the lower 16bit portions only. It's only in Extended
mode where HLz and DEz are used. Check out the instruction tables, you'll
see ADD HL,src is commented with X1 (meaning "in extended mode this
operation will use 32bit").
>I'm not really interested in an MSX380 100% compatible with MSX, if I want
>ot play MSX game or demos, I still have my MSX Turbo R or an MSX2. I think
>that the "new" MSX should free the power of the Z380 and other hardware to
>get a realy stong machine, the project paper sheet I've seen in Tilburg was
>very interesting, it was planing to use an enchanced version of the SNES
>(super FAMICOM) VDP for the video, I really prefer the the system is
>desinged to operate in 32bits to boost disk and memory access, using fast
>SRAM or maybe SDRAM.
I agree with you on this. Ofcourse, MSX380 could never be turboR (R800)
compatible, but then again turboR is more like "MSX Gaiden" anyway :)
I'm not so sure about that enhanced SNES VDP, because the SNES VDP is
pretty hard to program. I'd prefer the good old V9990 to be used, maybe
with some additional chips for huge sprites and rotation 'n stuff.
Greetz,
Patriek
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