Tech Flashback: Internal Modems

So earlier on, I made a few posts showing my external modem collection. First it started off with the Banksias, then the rest of them. Now it’s time for my Internal modems.

I think after this post is done, it will be evident why these came last. I do have a 3Com/USRobotics ISA modem, but that’s in a machine, so I didn’t take it out.

Lucent/Agere/LSI Chipsets

Lucent 1642C 33.6k Internal 16-bit ISA from Compaq – note missing speaker. Interestingly, this is a win-modem (meaning that some of the modulation/demodulation functions are handled in software) which depite being shipped as a 33.6k modem (depending on the card) could run at 56k depending on the driver installed.

Netcomm IN5699_4 V.92 Modem, based on the Agere 1648C Mars chipset. Lucent had been sold to Agere at the time, also a win-modem. In fact, I found these to be one of the most reliable and speediest modems I had ever used, and they were relatively inexpensive too. The use of a silicon line switch was susceptible to storm damage but that never happened to me.

Netcomm IN5699_3 V.90 modem – but don’t be fooled, it’s pretty much hardware identical to the one above. They’re both based on the Agere 1648C Mars chipset.

Rockwell/Conexant Chipsets

Puretek PT-3517 based on Conexant RH56D/SP chipset (Host Controlled – HCF family). This contains a hardware DSP which is controlled by the driver running in software – thus presenting less of a CPU load compared to full software modems without hardware DSP. This one is also special because it incorporates voice functionality in an internal modem – many of the modems meant for internal use don’t have this.

Skymaster (no brand) modem based on the Conexant HSFi. This is a cheap modem, with virtually no components because all the work is done by the CPU. This is almost just a sound interface to the phone line, much how Modios were (Smartlink). These were cheap and plentiful – here’s a few more in my boxes from other manufacturers:

Here’s one with just a single jack and no speaker because someone decided to save a few pennies.

This one has two jacks but no speaker.

This one is an initial HSF modem. Note it’s not an HSFi – the HSF nature is only evident in the code – RS56, rather that RH56. Otherwise, it looks like a pin-compatible drop-in for those who want to cheapen their RH56 based modems to become HSF modems instead – i.e. worse ones.


When it comes to ESS, everything is a drive. In this case, their modems took the name of “Teledrive”. Their sound cards were “Audiodrive”. It gets lame quickly. Their modems were a bit mixed and were on the cheap end of the market – available both in ISA and PCI. Commendably, the ESS ES2820S ISA modem has voice capabilities.

This is an ES2838S chipset modem. No idea how well it works, or doesn’t, but ESS has never been much chop in my books.


Yes, I’ve come across others. Like one which was Motorola based. But I don’t have one in my collection. I do have a 3Com/USR ISA 8-bit card that’s all covered and in my old box, so unfortunately that doesn’t get a showing. Other than that, there really isn’t anything else (at least, towards the late end of the 56k era when I started collecting these). The market is pretty much cornered by manufacturers who are selling either Conexant or Agere (now LSI) chipsets – regardless of brand. So there we are – internal modems.

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