Denys Beauchemin <[log in to unmask]> wrote:
> If I remember correctly, 100-BaseTx was much more a software thing
> on the HSC computers, hence the extremely expensive software.  On
> the PCI systems, the NIC do all the work and the system is not
> really aware of whether it's 10, 100 or 1000.

The "HSC" 100BT NIC was an HSC to PCI bus adaptor/bridge chip and a
Digital 2114X 100BT chipset (plus phy and such).

The "PCI" 100BT NICs are simply Digital 2114X chips.

IIRC, the HP-PB 100BT NIC was an HP-PB mothercard that contained an
HP-PB to PCI bridge, and then a PCI 100BT (not sure if was Digitial
2114X chips) daughtercard.

In broad handwaving terms, the quantity of work done by the NIC is
roughly the same. Certainly between the PCI and HSC NICs. Now, I have
to temper this with the statment that my expereince with the NICs has
been entirely on HP-UX, but I suspect that transfers over to MPE.
That being the case, the order of preference would be:

1) PCI
2) HSC
3) HP-PB

because the HP-PB driver had to do more work (not that the 100BT chips
did less) and achieved lower performance than HSC or native PCI.
While the HSC-PCI chip was mostly transparant to the driver, the HP-PB
to PCI conversion was not and one had to have extra interrupts and
such to get packets through everything.

On HP-UX at least, one would get higher performance with an HP-PB FDDI
card crippled with a 1500 byte MTU than one could get with the HP-PB
100BT card, and there was more to it than just the difference in
offering checksum offload... one will never see link-rate 100BT with
the HP-PB 100B NIC.

rick jones













>>
>> David N. Lukenbill
>> Computer Sciences Corporation
>>
>>
>>
>>
>> We just got  100 Base T for our 979-100 on MPE 7.0 from
>> [log in to unmask]
>>
>> The part number and cost were:
>>
>> B5427BA-340        100BaseT software, license, and manual for
>> HP 3000, Tier
>> 6
>> $1950.00
>>
>>
>> Connie Samuel
>> Clatsop Community College / Astoria, Oregon
>> 503/338-2376
>> [log in to unmask] / www.clatsopcc.edu
>>
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--
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                                     where do you want to be today?
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