USB vs. Serial

On 19-Mar-2004, Meindert Sprang lamented the demise of serial ports on comp.arch.embedded:

Why? What exactly is wrong with a simple, cheap serial port? It's only the fault of the current game-driven PC industry that serial ports become obsolete on mainstream PC's. I don't see any real technical reason why serial ports should disappear.

Ulf Samuelsson replied with a list of advantages of USB:

RS-232 cables are not easy to use for the average PC user. How much time have you spent trying to get RS-232 to work, and found out the cable was not suitable. A user simply cannot make those mistakes with USB. RS-232 means phones calls to the vendor. I do not know how many phone calls a user have to make for the vendor to lose money - they hate that
RS-232 connectors are more expensive than USB connectors.
RS-232 is limited to 115 kBAUD in std PC configurations. This is a pain when you have requirement for faster speed.
Each RS-232 port needs I/O and Interrupt. You do not have many interrupts on a PC.

Do you need more?

Call me an old fashioned curmudgeon, but I'm not convinced that USB is that much better. I replied:

With suitable cables and/or adapters, you could plug together almost any pair of EIA-232 devices. With USB that's generally not possible. For example, I used to have a PDA, a modem, and a computer all with serial ports. I could attach the PDA to the computers, or the modem to the computer, or the PDA to the modem.

My new PDA, modem, and computer have USB ports instead of EIA-232 ports. Now I can connect my modem to my computer, or my PDA to my computer, but if I want to connect my modem to my PDA, I'm just s*&$-outa-luck. This is reportedly "progress".

"USB On-the-Go" is supposed to address this, but it seems quite unlikely that it will ever have the degree of flexibility that EIA-232 connections had.

USB vs. EIA-232 is like a GUI vs. a command line. It makes simple things easy, and more complicated things impossible.

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Last updated 22-Mar-2004

Copyright 2004 Eric Smith

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