At 11:23 AM 11/29/98 +0600, you wrote:
>Is it tru?
>
> That Turbo-r have two cpu z80 & R800.
Yes, it's true.
Z80 is part of the S1990 engine, R800 is a seperate IC.
>Because R800 executing DJNZ & JR
>instruction another way for calculating destination address
I don't think so. R800 can execute all Z80 code in the same way as a real
Z80 does.
> Who know about characteristics of R800. I know about instruction time.
>I want know other characteristic. What will be? If i execute DBG in R800
>mode?
> Time for acces to memory and I/O?
When accessing DRAM, it only sends the CAS or RAS (forgot which one, it is
the lower one) if necessary. So accessing subsequent addresses is faster
than accessing addresses that are spread all over the address space.
I think this only happens with the internal mapper, because mappers in
other slots are a lot slower.
About I/O, the S1990 engine slows down the R800 to make sure MSX
peripherals (like V9958) are not accessed too fast.
> Has he burst mode?
> Has he 16 bits data bus? I think not
R800 is still an 8-bit processor.
Bye,
Maarten
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