Serial interfaces (was Re: Any former Psion 5 owners out there?)

Charlie Carothers csquared3 at
Sat Jul 24 22:38:30 CDT 2010

Tony Duell wrote:
>>> Just out of curiousity, do the USB-parallel adapters support all the
>>> low-level bit-twiddling that you can do on a real PC printer port? Can
>>> you treat them as 12 digital outputs and 5 inputs?
>> Nope,. They generally appear as a DOT4 printer device; in other words,
>> they make a parallel printer appear to the system to be a USB printer,
>> not the USB port appear to be a parallel port.
> Right... Pity...
>> But if you need the port, what's wrong with a Centronics parallel port
>> or a couple of RS232 ports on a PCI card? They are the "real thing",
> Nothing, provide the host machine has a PCI slot. There seem to be an 
> awful lot of modern PCs that have USB as the only expansion.
> -tony
Hi Tony,
I'm sort of surprised to hear you say that RS232 ports on a PCI card are 
OK with you.  Maybe it's because I'm primarily a software guy, but for 
some purposes I loathe RS232 ports on PCI cards almost as much as I do 
USB.  I think my loathing of both technologies is much the same as 
yours, in that in some cases they both make it more difficult for me to 
do precisely what I wish to do.  Just as one example, I have some legacy 
DOS-based software containing its own UART driver.  I don't even want to 
think about trying to make that work on a PCI card RS232 port.

BTW, I don't mean to imply that I unconditionally loathe these two bits 
of technology - just when they get in my way.  At other times, I greatly 
enjoy the use of both.

Charlie C.

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