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Date: Fri, 5 Jul 1996 20:36:58 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199607051036.UAA00165@godzilla.zeta.org.au>
To: bde@zeta.org.au, stesin@elvisti.kiev.ua
Subject: Re: muliport boards - building a PPP dialup server
Cc: hardware@freebsd.org, isp@freebsd.org
Sender: owner-hardware@freebsd.org
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>	So an idea to get a PCI board seems to be pretty reasonable...

If the PCI interface is actually faster.

>	Anyway, ISA is a dead-end, I think.  (Consider the following:
>	16 ports seems to be an upper limit for ISA card at 8MHz, even if
>	it's 16bit "smart" one -- simply because it's ISA.
>	PCI has 33Mhz => 4 times faster,
>	it's a 32bit bus => add two times more.  So PCI intellgent

Only for 32bit peripherals.  Not for 8-bit peripherals like 16550s and
cd1400s.  These have at most 1/2 the bandwidth of the ISA bus because
they use only 1/2 its width.  In practice they usually have only 1/5
the bandwidth of the ISA bus because they don't support insb/outsb.

>	card should be able to handle at least 8 times more ports
>	at full speed, => up to 128 ones!  And just today I have

The software overhead would be too large for more than 32 or 64 *
115200 bps on a Pentium.  Fortunately, modems can't sustain 115200 bps.

Bruce