:> As far as I know, RETI and RET work exactly the same in all respects,
:> and are different only in the exact instruction bytes, and the number
:> of T cycles they consume. My guess is, that RETI simply serves to
:> INDICATE that it ends an interrupt-routine, rather than a normal
:> subroutine. For the rest, it's my belief that these 2 instructions
:> can fully replace each other (so that you can use a RET wherever a
:> RETI is used, and vice versa). There IS a difference between RETN
:> (with NON-maskable interrupts) on the one hand, and RET/RETI on the
:> other hand, but did anyone ever find a difference between RET and
:> RETI (other than instruction bytes and T cycles)?
:
:RETI is used to signal I/O device, that the interrupt routine has been
:completed. Anyway as long as I know, MSX computers does not have any I/O
:device, that needs this information. If I'm correct it is used only by Z80
:family devices.
I'm not certain, but isn't a RETI the same as EI / RET???
I believe it was like this on the gameboy-processor and it seems the most
logical explanation to me, for RETN also restores the original IFF-settings
for an NMI-interrupt...
I could try it out...
~Grauw
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