[A83] Re: General programming questions
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[A83] Re: General programming questions
The instruction timings for the GB is different from the z80. There aren=
't=20
t-states like there are with a real z80. It's much easier to count cycle=
s.=20
If you want to directly compare it to the calculator's cpu, then it would=
=20
be more like 4mhz and 8mhz. Instructions like "or a" take 1 cycle, so yo=
u=20
can execute a million of them a second on the GB, or two million a second=
=20
on the GBC when running in double speed mode. Other instructions like "l=
d=20
a,0" take 2 cycles, instead of taking 7 t-states. There aren't any=20
fractional instruction times. This is likely due to the bus design.
RISC and CISC has nothing to do with the speed. The line between the two=
=20
is now blurred anyway. There hasn't been any proof that either design is=
=20
more efficient. For example, an Athlon is a RISC CPU that executes a CIS=
C=20
instruction set (x86). The front end decompiles x86 instructions into=20
simpler instructions that can be rearranged and pipelined, resulting in=20
much better execution speeds than a traditional x86 processor at the same=
=20
clock speed.
> Was this because this was a RISC processor, or does that relate to othe=
r
> things??
> The original gameboy had a clockspeed of 1 MHz and the colour version
> 2Mhz (I think...) , but seemed to be relativly fast, and this is a
> characteristic of a RISC processor, right, having a relativly low clock
> speed but being very fast because it has fewer instructions?
References: