Posted by Andy Warne on 12, 2001 at 9:02 AM:
In Reply to: 2 IPACs work fine (more) posted by Ron Michallick on 12, 2001 at 8:29 AM:
Using 2 I-PACs in USB mode, they are both treated identically as Windows loads 2 USB keyboard drivers, one for each board.
Using 2 I-PACs in PS/2 mode, there is no priority issue either. The second board sends to the first using an interrupt-based system and is given equal priority over the inputs on the first board which are also interrupt driven. It's just a case of who gets there first. The lag generated by the second board, from input being activated, to being sent to the first board is max 3 millisecs which would never be noticed.
The byte string from the second board is clocked into the first by the clock generating interrupts on each cycle, and there are 2 state machines, one bit-level and one byte-level which handle this so that the first board can still deal with any of it's own keypresses which occur during this operation. Sorry for technical detail overload!
:
: I dont know about using 2 USB IPACs or using
: an USB and a PS2 port, but if you use both IPACs
: (or any encoder) using the PS2 port in a "chain"
: Put the important (speed critical) inputs on the
: encoder closest on the computer. The second device
: in the chain will have more lag. This may or may
: not be an issue for you.
: Comments welcome,
: Ron.