They keep this 20+ year old laptop around because it has a serial port and every now and then that comes in handy.
You can’t really see it in the picture but the laptop is pretty thick and heavy.
They keep this 20+ year old laptop around because it has a serial port and every now and then that comes in handy.
You can’t really see it in the picture but the laptop is pretty thick and heavy.
USB serial adapters sometimes have compatibility issues. Hardware serial ports have interrupts, while USB serial ports can only be polled at a limited rate.
There are serial and parallel PCIe cards available that work much better than the USB adapters. Some modern desktop motherboards still have a serial port, but it’s usually a pin header that will need an adapter to connect to. There is also a nearly pocket sized laptop with a serial port and more connectors than many full size laptops have.
PCIe can indeed be your friend! I got one with parallel port and no device to connect to. Currently looking for ideas.
The parallel port used to be used for connecting all kinds of homemade devices like logic analyzers, microcontroller programmers, frame grabbers, or just used for GPIO for reading switches and controlling relays. It was a lot easier to access directly from DOS than it is from Linux or newer versions of windows though.
Of course you could just connect a printer to it. I’ve got a thermal receipt printer that I’ve been meaning to write software for eventually. It will print out whatever I cat to
/dev/lp0, but I can’t easily do any formatting or control the cutter that way.