HP-IL (was Re: HP9000 model 710 workstation(Apollo 700).)

From: Joe <rigdonj_at_cfl.rr.com>
Date: Thu Jul 18 00:28:05 2002

At 09:31 PM 7/17/02 -0700, Eric wrote:
>I wrote:
>>> It might use HP-HIL, Hewlett-Packard Human Interface Loop.
>
>Tony wrote:
>> Are you sure that's _loop_? HP-HIL is not physically a loop. It's a
>> point-to-point serial interface.
>
>It's my understanding that electrically it forms a loop, because the
>last device loops the data back. I could be wrong -- it wouldn't be the
>first time.

  I'm pretty sure that you're correct about the name but I don't understand how they know what device to put the "loop" into since almost any HP-HIL device could be the last one on the chain. For example, you might have only a keyboard, or you could have a keyboard and then a mouse or you could have a keyboard, a graphics tablet and then a mouse or maybe just a keyboard and a tablet. The possiblities are astronomical. IIRC you have have up to 8 devices on the HIL chain.

  Oh! And just to add to the confusion, the HP IPC has TWO HP-HIL ports. The IPC keyboard doesn't have a second port for daisy chaining to other devices so you're supposed to plug the (HP-HIL) mouse into the second port on the IPC. I've tried standard HP-HIL keyboards on the IPC and they work fine. I've also used the second port for a mouse with no problems but I've never tried daisy chaining a mouse off of HP-HIL keyboard attached to an IPC. Hmm, it might be interesting to put a keyboard and a mouse into EACH of the ports. (yes, I have IPCs to spare!)

  BTW I have two different manuals for the HP-HIL mouse and one manual for the HP-HIL keyboard and NONE of them tells what HP-HIL stands for!


    Joe
Received on Thu Jul 18 2002 - 00:28:05 BST