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

Tony Duell ard at
Sat Jul 24 16:27:16 CDT 2010

[USB-Centronics adpaters]

> They work *remarkably* well with even old printers, in my experience,

That's not too suprising. The Centronics interfaec was pretty well 
standardised, and it's fairly simple anyway...

> but not any other parallel-port device, AFAIK. Same as the USB floppy

Incidentally, I've sort-of had the revers problem, but not with USB. With 
HPIL. The HPIL-GPIO intefaces (HP82165, HP82166) will talk to a 
Centronics printer with no problem at all. But they identify themselves 
to the HPIL controller as an interface device (which they are), not a 
printer. Which means some HPIL machines (the 110 nd Portable+ laptops 
being obvious examples) will not recognise such a set-up as a printer and 
won't print to it. This is entirely a software problem, with the right 
drives it will work. Fortuantely the machine I use the most, the HP71B, 
has the admirable policy that it will do what you tell it to do, even if 
it may be a bad idea :-). Anf it will happily print to a Centronics 
printer on the other side fo an HP82165...

> drive chips: they only talk to 1.4MB drives and can't do GCR and so
> on.

I wouldn't expect them to do GCR (most PC internal controllers can't). 
But I suspect they can't do FM (single density) either. Can they handle 
250kbps (360K, 720K) or 300kbps (360k disks in a 1.2M dribe basically) 
data rates? Or do they assume tat everything is an HD 3.5" disk?

> More of the sad commoditisation of the computer industry, the descent
> to a lowest-common-denominator: the X86 PC. :=AC(

But it's worse than that. Things that I can do (and do do) on my 80x86 PC 
are not so easy to do on modern machines.


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