Serial interfaces (was Re: Any former Psion 5 owners out there?)

All decent buses allow you to share interrupts -- the ''design' of the interrupt suystem on the ISA bus is one reason to hate that bus.. Very well designed buses (Unibus :-)) have each card send an interrupt vector which directs the CPU to the right ISR. One others (e.g. HP's DIO-1 bus, the ISR has poll each card using that interrupt level to see if it's the source of the interrupt. I assume PCI does something like that, Nor me. as I said, I don't own a PCI machine (and probably never will) YEs, that was part of the 'no configuration links/switches' idea. I am not sure thats' a Good Thing, but it can't be too hard to work with. Plenty of machines, including many classics, had some form of autoconfiguration. Having doen battle -- and won -- with the HP71's automaticlaly coffiguriuig nmemory, I can't beelive this is any worse. The ISA bus is easy to design cards for (it's basically just the 80x86 bus) but it does have that horrible interrupt system. The idiot who came up with the idea of active high, edge triggered, interrupt should be condemned to spenmd eternity in a part of hades having to design complex ISA cards and write drivers for them. He would then realise wby everyone else used active low level triggering. Alas not. But PCI is notably harder to design for than many of the older buses, which may well also not have been designed with the hobbyist in mind,but at least a serious hobbyist could wire-wrap an interface card and expect it to work. -tony