Don't know where to find that paper, but it reminds of a friend at UNSW (in Sydney) that used to instrument the OS9 kernel by setting and clearing bits in the parallel port.
The monitoring hardware was indeed simple - an analogue voltmeter connected to the bit of interest to produce a simple but effective short term average. For example, a bit that is cleared when in the system idle loop produced a 'tacho' style analogue load meter. That must have been in the early 80's, but I still find the parallel interface a good method of getting real-time diagnostics, or front panel style indicators for statuses such as system/user mode. Consequently I don't welcome the current trend toward optimising them out of new hardware. USB parallel interfaces may be ok for driving printers, but they are no substitute if you want a very low overhead, low latency i/o mechanism. Regards, DigbyT On Tue, May 27, 2008 at 06:54:58PM -0400, Pietro Gagliardi wrote: > No, I wasn't around that time :-) But I was looking for the Hello > World X11 paper a while back, which was pre-website USENIX. But on the > USENIX website it seems that you can purchase papers from before > 1991(?). Perhaps they had a paper? > > On May 27, 2008, at 6:02 PM, ron minnich wrote: > > >OK, this is a long shot, but i'm running out of ideas. > > > >Long, long ago, at a Usenix, I saw a talk by some adventurous > >australians (are there any other kind?). It was concerning some neat > >hardware designed for kernel monitoring. > > > >They had done a very neat hack. Basically, they modified the C > >compiler so that, on function entry and exit, the code would emit a > >16-bit quantity to the parallel port. They had some simple hardware to > >grab the data. > > > >WIth this, they were able to get some nice kernel performance numbers, > >all for the (low at the time) cost of an outw to the parallel port. > > > >OK, I have done some searching and can't find this. IIRC it was > >pre-website usenix. I am going to UCB this week and may have time to > >hunt it down in the paper archives, but ... just wondering ... anyone > >else remember this? > > > >thanks > > > >ron > > > -- Digby R. S. Tarvin digbyt(at)digbyt.com http://www.digbyt.com
