> >On the MSX interrupts the interrupt ends with a EI:RET. (No RETI, it has
no
> >use).
>
> But it has a reason I forgot. What's the actual effect of RETI? What are
> the differences with an EI/RET? And with an EI/RETI?
Well according to the documentation the purpose of RETI is so
interrupt-generating cartridges can detect when the interrupt ended by
polling the databus. However, this is not supported on MSX since even the
BIOS doesn't support it.
So RETI on the MSX is only a slow variant of RET.
I think on some other processors RETI has an EI instruction integrated in
it, just like RETN has in the Z80. But on the Z80 RETI hasn't.
~Grauw
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