[rescue] Parallel ports [was Re: Slightly OT: ?Bad Cap Saga]

Peter Corlett abuse at cabal.org.uk
Thu Aug 21 09:38:11 CDT 2008

On 21 Aug 2008, at 14:49, John Floren wrote:
> I think I could probably deal with losing the parallel port (Goodbye,
> dot-matrix printer) but the worst thing is the way it's getting harder
> to get real serial ports. As with these parallel ports, the serial
> hardware is on the motherboard, there's just nowhere to connect a
> cable. They tell us to use USB to serial converters, but I do a lot of
> debugging with serial consoles on Plan 9, and USB-serial doesn't work
> so well there :(

I've not looked closely enough at the spec sheets for the USB  
chipsets, but you can probably still write simple polled-I/O code to  
splurt bits out of a USB serial dongle. It's not going to be as simple  
as talking to a 16550, of course.

The greater loss to hardware hackers is definitely parallel. With  
parallel you can build bit-banging interfaces which are out of the  
scope of a USB printer cable. But with serial you're not really going  
to be doing much more than exchanging serial data and USB serial  
adaptors work just fine at that.

(Although you *can* bit-bang with a serial port if you're feeling sick  

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