24 Nov
2008
24 Nov
'08
10:41 a.m.
>It's a 9 pin dot-matrix head which is tilted
mechanically (a pair of
>solenoids shuttling a shaped core to and fro inside the carriage) to give
>18 pin resolution in 2 passes. I find them interesting because of that
>curious mechanism.
[...]
I have two LA100ro as they proved in the field to be rugged and I got to
see that from the point of view of DEC printers engineering. The curious
approach to "18pin" printing was twofold. One was to allow fast draft
quality printing and the other was rugged high quality printing that could
still punch multipart forms with a known reliable head. At that time there
were a few 18 pin heads but they didn't have the long term life at sustained
high print rates. Note, this is a 1984-5 design so understand that many
printers at that time were of smaller or less rugged style or really
imposing printers.
Sure. The idea of using multiple pases to increase resolution was quite
common at the time. Sanders Associates made a range of 7 pin printers
with an accurate paper feed mechanism which did 8 pases for some fonts,
and the result looked as good as and daisywheel I've ever seen. But the
DEC trick of shifting the printhead vertically I think was unique to the
LA100 printer, and it's interesting to me for that reason.
But as I've said many times before, I like unusual/curious designs
whether they're processors or not. So the LA100 printer (and indeed the
Sanders models I've just mentioned, which have some interesting
electronics) are things that I am glad to have in the collection.
-tony