plotters again

[Brent Hilpert]

Tony Duell wrote:
> Brent Hilpert wrote:
> > Or how about this: pretty much every lesson learned and development made in
> > languages and programming of the last 4 to 5 decades is missing.
> 
> Considering the machine is 3 decades old, that would partly explain that...

Em. on partly.
Regardless, it doesn't make the programming any less tortured today.


> I assume this plotter ahs a 'listen only' mode, where it's selected at
> power-on and doesn't need ot be addressed. Many HP plotters do.
> 
> Of course you lose some functionality if you do that. Most HP plotters
> are HPIB talkers too, they can report the current plot size and pen
> position -- you could move the pen around with the buttons on the plotter
> and use the machine as a primitive digitiser (put a trace from some other
> instrument on the plotter bed, then move the carriage to points on that
> trace and read them into the computer). You might well not need this though.

The 9815 interface supports the digitising functions regardless of the
(non-)addressability issue, so that functionality is not lost. (My unit
even came with the digitising sight.)

>From the schematics, the 9815 interface asserts a signal on the special
connector on the plotter, said signal ends up on the plotter microprocessor bus,
so the plotter microproc is distinguishing 9815 vs HPIB and acting appropriately.