You can use the jack for anything which has an IR blaster, preferably a blaster with a 3.5mm plug.
A fellow called Gary Gray, over at Tivocommunity.com forums, has developed an adapter cable, so that a Series 1 or 2 TiVo can directly control a DTA, with no IR blasters.
I have recently benched my 8910 (worn buttons), in favor of an 8820. I never needed the LCD or backlight, and the 8820 has the keys I need (I have most of my OEM remotes to fall back on or even learn from).
The 10820 is a little more the shape and size of the 8910, but still lacks the LCD and ...
If you do realize that most IR protocols use a device/command scheme, meaning device code is the same for all the buttons, just the command code changes, it is pretty easy with KM or RM to make an upgrade.
For just 8 buttons, using a fixed device code should be fine.
I don't need one. I have fixed AC lights behind my HT system. Well, just one, an vintage fluorescent tube bed light from the 1940s (uses a T8-12 tube), and a handheld reflector fixture with a 1W LED bulb (it would normally accept a 60W bulb). Above my TV watching seat, I have a dimmable incandescent ...
Well, for the JP1 remotes, you have to assert (lower) the Reset line on the remote to read them. It can be assumed, when Reset is not asserted, that it is safe to unplug the remote.
As for orientation, of it doesn't read correctly, then it can be assumed it is incorrectly connected.
Normal PC serial ports, and the USB to RS232 adapters use level converters to drive the TTL to the +/- 5 to 12V levels.
The JP1.2/3 interface uses TTL. The basic interface converts between +/- and TTL. Tommy Tyler's JP1.2/3 USB adapter directly uses the already TTL on ...