Re: (PMOD) HSP/HSF/HCF/etc.

Ed Schulz (edschulz@lucent.com)
Wed, 14 Jul 1999 09:30:44 -0400

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Previous message: Jeff Northon: "(PMOD) Modem suggestions"
Maybe in reply to: Craig Baird: "(PMOD) HSP/HSF/HCF/etc."

I don't work for Lucent RABU wrote:
>
> On Tue, 13 Jul 1999, Craig Baird wrote:
>
> > I keep seeing messages form people asking about modems using these
> > various chipsets. The only one that I've ever actually seen in real
> > life is the Rockwell HCF (although it seems I vaguely recall seeing an
> > HSP once, but I can't be sure). Do these other chipsets (HSP, HSF)
> > actually exist? The reason I ask is that someone recently posted asking
> > something about firmware for an HSP modem. Someone else responded back
> > suggesting the Zoltrix firmware, as if it were an HCF. So, do these
> > modems exist, or do these people really mean HCF?
>
> My bad for causing confusion.
>
> HCF is a rockwell chipset, I haven't researched to see what it actually
> stands for.
> HSP is Host Signal Processing. It's the industry trend to off-load
> processing from the modem itself and have the CPU of the computer handle
> the workload. I think any modem that uses .vxd and doesn't require a
> firmware update is in this category. (I could be wrong and Ed S. can
> correct me ;)
> HSP modems would be like Rockwell HCF, PCTel, Lucent LT winmodems.
>
> So HCF is an HSP, but HSP is not necessarily an HCF.

Since I was invited to correct, let me take the opportunity.

3Com USRobotics WinModem, Lucent Win Modem (Apollo ISA 1641/2/3/4, Mars PCI
1645/6, Leo "WildWire" 1690 DSP), and Conexant HCF are all host-controller
modems. (I imagine that HCF stands for host controller function.) The
hardware includes a DSP to handle the signal processing, but the Windows
driver needs to control the DSP, handle the Windows interface, and perform
some LAPM or MNP protocol functions.

HSP stands for host signal processing, also known as a soft modem. The
Pentium does everything in a soft modem. The hardware only includes the
analog line interface, codec, data buffer, and PC bus interface (ISA, PCI,
CardBus, AMR, etc.) -- but no DSP chip. PCTel is in this category. The CPU
load of a soft modem is significantly greater than for a host controller
modem.

So you got it backwards: HSP includes the controller function by necessity,
but HCF is not necessarily HSP.

-- 
Ed Schulz
edschulz@lucent.com
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Previous message: Jeff Northon: "(PMOD) Modem suggestions"
Maybe in reply to: Craig Baird: "(PMOD) HSP/HSF/HCF/etc."