What is the AMR slot?

Misha asks: "I just started catching up on hardware info, and it seems many new chipsets (Apollo KX133, etc.) and motherboards are supporting this new type of slot. Seems to be a substitute for ISA if you are using it with a sound card or a modem. Not sure what the advantage is, but I assume it has something to do with letting ISA go. Can enlighten me some more about it?"

AMR stands for..

[scjody]

AMR stands for Audio Modem Riser. <GUESS> Since it seems to exist on boards with built-in sound support, it probably provides the regular ISA services plus some sort of direct connection to the mobo's sound chip, which could be useful to a winmodem.</GUESS>

duh.

[Zurk]

its a small port for connecting the motherboards winmodem to an external pinout. basically plug in a small circuit board into the mobos winmodem AMR slot and connect the RJ45 to the circuit board. its pretty stupid.

Re:duh.

[atallah]

Wrong.. it is not a just a connector, it is a "real" slot, you can buy AMR modems and sound cards. They are cheap, DFi makes an AMR modem that you can get for $25, you can get a generic for $15.

Another advantage is...

[MattT]

Internationalization(sp?), that is - if you split the digital from the analog circuitry of a modem, then you're putting the smallest amount of hardware that is unique to your local/national phone system on the (cheap!) expansion card.

Re:AMR stands for..

[TRS-80]

AFAIK, it is for winmodems and winsound cards. The idea is that you put just the bare minimum circuitry required for a modem or sound card on the extension board, and let the CPU perform all the work that normal sound cards/modems perform on the expansion board.

The idea of this is to provide cheap add-on modems and sound cards for budget PCs, as these are very cheap to implement when you offload all the processing to the CPU. While these may be good for low-end users, for any serious PC gamer the CPU usage of these solutions makes them unacceptable IMO.

Winmodems (and probably winsound cards) currently have virtually no non-MS OS (Linux, BSD, BeOS) driver support, another reason to avoid them. Personally, I think they're the spawn of the devil, reinforced by my recent exposure to a 56k winmodem that went full speed for 5-10 min before slowing to a crawl.

I don't think it's on the ISA bus; Intel and several other chipset manufacturers are trying to eliminate it (this will provide a small speed boost.) Try looking at some motherboard reviews for more technical details; offhand there's a few at anandtech.com

Re: Open Source support for WinModems

[Jimithing DMB]

Actually, you can try the LinModem site [linmodems.org] for information and preliminary code for getting your winmodem to do neat stuff under Linux.

There is a bit of code for Lucent based modems allowing you to do full duplex audio. There is also some code for a CL-MD5620DT (Cirrus Logic) which includes code for modem emulation.

What needs to be done is this:

1. Some sort of device for the modem which would allow it to be completely controlled (as in pick up the phone, hang up, send out this audio stream, receive an audio stream).
2. A modem emulation package with support for v.34, v.90 and all the other good standards.

Currently all of this is done in user-space. It would definitely be better to do #1 in kernel space with interrupts instead of polling.

There is already a modem emulator with 14.4 speed and DTMF dialing capability. The only thing it really needs is a bit more work to do v.90 and everything.

Dave.

AMR is...

[rogersfx]

...supposed to be a way to get better signal quality. Lots of manufacturers cut costs by putting modems and sound chips on the motherboard. The problem is that the motherboard is electronically noisy. This makes for buzzing in your speakers and data errors from your modem. The AMR slot is a way to put these components up away from the mobo without drastically increasing costs. Read more here [intel.com].