🚀 go-pugleaf

andrewsh@lonex.radc.af.mil (Harold G. Andrews II) writes:

>them any more) and the new 32 EISA cards.  You probably won't notice any 
>improvement in performance using the 16 bit cards in an EISA slot (though I 
>could be mistaken).  You will, however, see a sizable increase in the speed 
>with EISA cards in EISA slots (as opposed to an ISA card in an EISA slot
>with the same "purpose in life" as the EISA card in question).

Basic improvements of EISA are:

		32-bit bus
		33 Mhz
		Level trigged interrupts
		Bus-mastering

Level trigged interrupt allows, that the same interrupt can be shared
for a many different cards (if nesseccery). How it happens, is i.e.
two cards will give interrupt at the same time. All right, EBC (EISA
Buss Controller) will scan all those slot-specified I/O addresses, that
'was it you, who wanted a interrupt' and gives it. If the interrupt
is still asked, then EBC will again scan those I/O addresses, that
who has been without IRQ.

So we have extra I/O addresses for every slot/card.

And we don't have more IRQs than ISA bus has. But EISA (only EISA)
cards can share them, so it will not be a problem.

Bus mastering is not anymore DMA-based like in old ISA-machines. Now
it is truth busa-mastering. It will help a lot, that the card can
do lots f work without loading the CPU.

Then we have ofcourse PS/2 styling configuration system for all EISA-
cards. SO the configuration of EISA (ISA cards can be used, but not
needed to be configured) cards is stored in the PC, and the BIOS will
check in every boot, is that information correct. Normaly those EISA-
cards are a little bit smarter, so we don't need to chance any jumpers
to chance the IRQ, DMA aso. You can do it by EISA-configuration prg.

About the future of EISA. I would say that it is very good, if we are
thinking about the future. The I/O will not be the bottleneck for a
years. Harddisks and memory are now adays. I have used the Mylex
EISA SCSI-controller under a Unix, and I have to say it is lovely.
Mostly it is because of cache, but busmastering and EISA makes wonder-
full things. What do we do by the fast cache, if our DMA maximum
speed is 8 Mhz? Nothing.























-- 
---------------------------------------------------------------
Matti Joutkoski, mattij@yj.data.nokia.fi, tel. + 358-0-5673866.
---------------------------------------------------------------