>> > But... I have read that R800 works at 28 MHz.
>>
>> I have heard this same rumour, but if I'm correct this means, that R800
>> works with 7 MHz clock, but it is as fast as 28 MHz Z80.
>
>But hasn't it an 28 MHz crystal? Because some people (like Erik Maas) have
>made it run on 40 MHz, by replacing the oscillator-crystal... How can you
>explain this? Is the 40 MHz not really 40 MHz?
I think there is a comfussion here. The frequency of the clock is a physic
measure. That is, it measures the number of clock ticks in a second. So, 28
MHz are 28MHz even in the case that an instruction needs 1000 cycles. If the
Z80 needs 4 cycles to run an instruction is a different thing. I'm not sure,
but I presume that, due to the instructions of 3 and 4 bytes it would need
more than 4 cycles. But, supposing it needs 4 cycles (and supposing a
3.58MHz clock for the Z80), it runs at (3.58 / 4) MIPS.
What I want to say is that the MHz are an external measure. When speaking of
the MHz of a processor, we're speaking about the frequency of the clock. And
is more correct talk about MIPS that about "internal MHz".
Then, I think that R800 works at 28 MHz (it has a clock of 28MHz). I don't
know the MIPS (Milions of Instructions Per Second) of the R800, but probably
the ratio MHz / MIPS is near 1 (that means between 1 and 2), because of the
RISC architecture. But R800 is RISC, and that means that it needs to execute
one or more instructions to do the same functionality of one only
instruction of the Z80.
Is this correct?
Another question... I'm interested on the Z380 project, but I have readed
that, when the japanese companies planned to make the MSX2 (there are a few
years!), they want to use the Z380... Is Z380 an old chip? Is a good choice?
Will be faster the Z380 than the R800? If is faster than the R800, it will
be faster enough to allow the R800 emulation (for TR compatibility)?
And... what about omega project? I have emailed with Rafael Corrales, who
works in the Z380 project, and it seems to work good, but I have heard
nothing about Omega Project.
+------------------------------------------------+
| Toni Burguera Burguera |
+------------------------------------------------+
| E-mail : [EMAIL PROTECTED] |
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| 9D - La Novena Dimensio |
| http://www.geocities.com/Area51/Dimension/9812 |
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