PCTel Modems
There are a number of different types of PCTel winmodems available, some of
these are PCTel boards, some are integrated into motherboards. Some use PCTel
chipsets, whilst other do not. Currently we can break the modems down into
two explicit groups: PCI Modems and AMR (Audio Modem Riser) Modems.
PCI Modems
The PCI Modems consist mainly of a DSP (Digital Signal Processor) and various
other hardware, mounted on a standard PCI card, but accessed through a custom
interface designed by the modem manufacturer. There are three common groups of
PCTel PCI Modems:
| PCT789
| These modems are commonly refered to as a PCTel HSP
MicroModem 56 and have very similar hardware with each model representing
slight improvements over the previous one. The name comes from their
PCI Id, which is of the form 134d:789x, where x is a number between 0 and 7:
| PCI Id | Description | Chip |
|---|
| 134d:7890 | PCTel HSP MicroModem 56 | PCT789T-C1 |
| 134d:7891 | PCTel HSP MicroModem 56 | PCT789T |
| 134d:7892 | PCTel HSP MicroModem 56 | PCT789T-A |
| 134d:7893 | PCTel HSP MicroModem 56 | S911 K017 |
| 134d:7894 | PCTel HSP MicroModem 56 | FT13 |
| 134d:7895 | PCTel HSP MicroModem 56 | PCT789T-C1 |
| 134d:7896 | PCTel HSP MicroModem 56 | PCT789T-C1 |
| 134d:7897 | PCTel HSP MicroModem 56 | PCT789T |
|
| PCT688T |
This modem is commonly referred to as a PCTel Oasis
Modem. It can be recognised by its PCI Id:
| PCI Id | Description | Chip |
|---|
| 134d:2180 | PCTel Oasis Modem | PCT688T |
|
| CM8738 |
This modem is branded as a C-Media CM8738 Modem
and is easily recogized by its PCI Id:
| PCI Id | Description | Chip |
|---|
| 13f6:0211 | C-Media CM8738 Modem | CM8738 |
|
AMR Modems
The AMR Modems are slightly more standardized in terms of the boards and the
interfaces to the computer. They are either mounted on a small daughter-board
(smaller than a PCI card) or are mounted directly on the motherboard
(particularly in laptops). Basic access to the modem is via an AC'97
Controller, which provides a standard interface to some of the modems
functions, however much of the modem is written in software and makes use of
the custom chips hidden behind the AC'97 Controlled to actually act as a
modem.
There are several AC'97 Controllers which can have PCTel modems behind
them, with several from Intel, and other from SiS and VIA:
| PCI Id | Description | HAL |
|---|
| 8086:2416 | Intel 82801AA (ICHAA) AC'97 Modem Controller | i8xx |
| 8086:2446 | Intel 82801BA/M (ICH2) AC'97 Modem Controller | i8xx |
| 8086:2486 | Intel 82801CA/M (ICH3) AC'97 Modem Controller | i8xx |
| 8086:24c6 | Intel 82801DB/M (ICH4) AC'97 Modem Controller | i8xx |
| 8086:7196 | Intel 82440MX (Banister) AC'97 Modem Controller | i8xx |
| 1039:7013 | SiS AC'97 Modem Controller | sis |
| 1106:3068 | VIA AC'97 Modem Controller | via686a |
Identifying an AMR- or AC'97-based modem is much less straightforward
than identifying a PCI modem. The PCI Id that we see is that of the AC'97
Controller and not that of the modem. To identify the actual modem (or modem
codec as it is known) we need to interrogate the AC'97 Controller and
obtain the AC' codec id. This usually takes the form of three letters
(denoting the manufacturer) and a number (usually in decimal, but sometimes in
hex) which identifies the device:
| Codec (dec) | Description |
|---|
| DT2-49 | (PCTel Delta?) |
| DT2-50 | (PCTel Delta?) |
| SIL17 | Silicon Laboratories Si???? (PCTel Stinger?) |
| SIL33 | Silicon Laboratories Si3038 (PCTel) |
| TRA9 | TriTech |
Linux Support
There are Linux drivers for most of these devices. For 2.4 kernels all but the
Oasis model are supported. For 2.6 kernels, the PCT789 series and CM8738 are
supported by one driver, and the AMR modems by another.
The original drivers for all of these modems were produced as closed-source
modules for the 2.2 series of kernels. Through some dedicated work, the PCT789,
CM8739 and AMR modems are well supported under 2.4. Currently only the PCT789
and CM8739 modems are supported by the PCTel driver under 2.6, though some of
the AMR modems are supported by the SmartLink driver (in particular those with
a SIL33 modem codec). The PCTel drivers can be downloaded from
linmodems.technion.ac.il
The 2.6 driver is still being developed, and my thanks goes to Gustav Brabieri,
Jeff Trull and Philip Brooks (whose company DMX Music actually donated a modem to
the project) for getting this new driver off the ground.
The Oasis chipset is NOT well supported. The original driver has not really
been worked on since 2.2, and my attempt at a 2.4 port has been unsuccessful
(mainly because I don't have accesss to one of these modems). Experimental
support under 2.6 may be obtained using the SmartLink driver.
If you are not sure which modem you have, then download and run scanModem
from linmodems.technion.ac.il.
