Uphill, both ways

22.11.2009 18:47

Look what I found today:

D-link DE-620

It's an old DE-620 Ethernet adapter that was manufactured by D-Link. This used to be the only way I could get onto an Ethernet network with my Compaq Contura 4/25cx.

It has a parallel port connector on one end (largely obsolete today) for connection to a host PC and a 10BASE2 (thin coaxial, very obsolete) and 10BASE-T (UTP, common today) connectors on the other. This device had wonderful support on the old 2.0.x series of Linux kernels.

I can't recall what kind of bandwidth I could get with it, but I believe it was several orders magnitude better than a serial modem connection (especially since Contura's UARTs could only manage 9600 bit/s), but slower than the theoretical 10 Mbit/s for Ethernet.

Another curiosity was that it required external power through a power brick that's rated at 12 V and 500 mA (parallel port didn't provide power to devices). Today I guess I could almost run a complete EeePC with those six watts of power.

Posted by Tomaž | Categories: Digital


Didn't those parallel ports have speeds somewhere around 200-400Kbits/s?

Whatever it was, it was surely the limiting factor.

Yes, communication through the parallel port was probably the limiting factor.

Wikipedia states theoretical maximum of 4 Mbits/s for an IEEE 1284 port, but as I recall a parallel port in those times basically meant a latch connected to the ISA bus. No DMA or anything fancy like that. So the speed was likely limited by how much CPU time you had to spend reading or writing to port.

Posted by Tomaž

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