[BRLTTY] INKA switches

[Jason White]

Dave Mielke <dave at mielke.cc> wrote:
> [quoted lines by Jason White on 2011/10/26 at 14:19 +1100]
> 
> >I just tested with several combinations and yes, it does detect the settings
> >on startup.
> 
> It's been a while. I forget which way the switches are laid out. The one we 
> call "disable sensors" seems obvious. There are two others, "show sensors" and 
> "braille keyboard", which appear to be implemented but I forget what they do. 
> The fourth, "scaled vertical", doesn't appear to be implemented since the 
> switch to key tables (probably because there wasn't a good way to test it at 
> that time). Can you please verify? 

The top left switch turns sensors on/off, both vertical and horizontal. The
bottom left switch is supposed to scale the vertical sensors for screens that
have more than 25 lines. Remember that the vertical sensors are labeled in
braille (2, 4, 6, 8, ...) and that there is a vertical line next to the other
sensors.

Switch 3 (top right) controls the protocol feature whereby a full cell is
displayed adjacent to the corresponding horizontal sensor.

Switch 4 determines whether braille keyboard mode or qwerty keyboard mode is
in effect. In braille keyboard mode, the keyboard table is internal to the
device, as I recall.
> Perhaps, now that you have your Inka out of 
> storage, we can get it working again.

Yes, although I'm not sure how the hardware is going to hold out. Some of the
pins are already jumping up and down sporadically when a full line of text is
displayed. They settle down within 5 or 10 seconds, but they shouldn't be
doing this at all. When this device was last serviced, one of the cells had
failed due to deterioration of the insulation between the two layers in the
piezoelectric bimorph, and this could well be affecting other cells as well
now. At the time, it was possible to replace the failed cell with components
from a Telesensory PowerBraille which the service engineer had on hand.

On the positive side, it's a 1996 display that had heavy use in its day, so I
suppose this is quite a good record over-all.

Incidentally, the servicing was carried out by Nigel Herring
(http://www.pentronics.com.au/) whom I would thoroughly recommend to any
Australian readers who need braille displays cleaned or serviced. In fact, as
far as I know, he is the only specialist in braille display hardware in this
part of the world.