ISDN ``modems''

Since they don't actually do any {de,}modulation, they're actually referred to as terminal adapters. Whatever. You plug them into your serial port and they let you talk to another computer.

I'm wired!

I have an ISDN line at home now. BellSouth is charging me $60/month for it, which is a little steep, but they're a bunch of dumbfucks who would rather pull 24 pairs of copper to an ISP than run a PRI over one pair. Well, at least that's how their rate schedule is rigged.

We have a BitSurfr Pro attached to a rinky-dink i486 DX2/66 with a serial cable and get up to 9.1KB/sec. Before the Motorola ROM revision J, the BitSurfr was unable to keep a 2B connection alive to the Livingston 5BRI card, but now things seem rock-solid.

Now I'm buying a TC-200-S6-1 serial card to try to increase my throughput. That card has a 16650 UART (like a 16550 in that early versions of the chip were very broken. different in that it has 32-byte FIFOs instead of 16-byte FIFOs) and can do 460 kilobits/sec (the BitSurfr can only do 230Kb, but my old card only did 115Kb). Hopefully I can get better than 9.1KB/sec once I get the card working.

I also sent a card to Theodore T'so, so he should be able improve Linux's support for this kind of card. With the availability of ISDN TAs and their appetite for bit rates, it will be swell to be able to run things with a $29 dumb fast card instead of a $262 smart fast card.


Robert Forsman <>
Last modified: Mon Oct 14 14:59:19 1996