Conecting new printer to a 286

[Tony Duell]

> 
> On 07/04/2010 08:30 PM, Tony Duell wrote:
> >
> > classic HP machines (although what I do when I run out of the special
> > sprocketed thermal paper is another matter...).
> >
> >    
> Ask me for my unused stock ?

Possibly :-). Although don't you need it for your 7245? 

If you don;t ahvea 7245, try to get one. It's a curious machine, 
typically 'HP' of the period. Basically, it's a 12 element dot matrix 
thermal printer with the elements arranged in a diagonal-ish line on the 
printhead, along with an extra eleemnet in the middle. And a pair of stepper 
motors, one to move the head, the other to roll the paper back and forth.

The HPIB version (whcih is what I have) responds to 2 HPIB addresses. 
Data sent to one is taken as text to print, using the 12 elements. The 
reason they're diagonally-placed is so that it can print vertically just 
as easily as horizontally. Data sent to the other address is taken as 
HPGL commands and plotted, using the extra eleement (which is controlled 
so that you get a constant print intensity, no matter what the plotting 
speed is). And yse it can plot text too...

Electroinmcally there's an HP custom microprocessor ('nanocontroller'), 
ROMs, RAM (2114s...), and quite a bit of TTL for the HPIB interface and 
motor controller (which is quite interesting in itself).  And the PSU is 
a strange 2-stage SMPUS thing. 

As I said, a machgine to track down if you don't have one.

One word of warning. If you take the mechanism totally apart, you need a 
couple of (easy to make) special tools) to put it back together again. 
And there are a couple of tricks that make life a lot easier. Ask me if 
you want to do it.

-tony