About the HCF modem - Introduction
Rockwell, now Conexant, doesn't make modems - they make chipsets and develop the firmware/drivers and sell them to various modem manufacturers. The "HCF" chipset is actually a single-chip PCI software-modem (controllerless, aka Win Modem). A number of computer manufacturers, including some (like Compaq and IBM) who had been bundling the Lucent LT Win Modem, are including this modem with new computer systems. A number of OEM's (including Diamond) are retailing modems based on the HCF chipset. If you have one of these modems, this page might help you; if you don't have one, I do not recommend purchasing one. While some users are able to get good 56k connections with this modem, there are many connectivity problems with this modem - especially with older driver versions.
There is a variation of the HCF chipset that includes sound card and modem functions (used by HP and others). Also known as "Riptide", the modem portion of this product is the same as modem-only HCF modems. The Riptide is also made as an HSF/Soft modem combo.
Like the LT Win Modem, and USR Winmodem, the Conexant-based HCF modem has no flash memory and no hardware controller. The 'firmware' is a virtual device driver for the Windows operating system. And, like the LT Win Modem, you may be able to use firmware from a source other than the original supplier of the modem to try and get it up to speed. It should be noted that there are variations in design of modems using HCF chips - including "old" and "new" (V.90 and V.92) variants - so substituting a driver from a different source might result in the loss of some "advanced" functions (ie, voice, etc), or may result in the modem not working. There is a list of vendors and driver links on the HCF Drivers page.
One of the biggest factors in getting good 56k connections is the quality of the firmware or driver that implements the 56k protocol. The biggest factor in what modem is bundled with your (Compaq, HP, IBM...) PC is how cheap it is.
More information on the chipset and features is available on the Conexant (formerly Rockwell Semiconductor) site [keep in mind much of the information is vendor hype]:Conexant Desktop Modem Products
Also see: Annex Bulletins - Compaq's Rockwell Modems