lindsay@MATHOM.GANDALF.CS.CMU.EDU (Donald Lindsay) (08/23/89)
In article <1877@brwa.inmos.co.uk> davidb@inmos.co.uk (David Boreham) writes: >In article <21352@cup.portal.com> mmm@cup.portal.com (Mark Robert Thorson) writes: >>The 386 and beyond have both device type and mask stepping numbers which >>appear in one of the registers (DX, I believe) following reset initialization. >Yes, this is fine and we do it. Unfortunately it gives you the added >problem that you need to update the ID on *every* change to the device. >Sometimes the changes required to change the ID are more work than the >actual bug-fix or whatever. It's very intelligent of Intel to do this. The nice people at Inmos are hopefully aware that all those small bug fixes can CAUSE bugs, too. I first encountered this idea on the PDP-9, which had an instruction added just so that the software could tell PDP-7's from PDP-9's. The highest flowering that I know of is on the ETA-10 system board, where the diagnostics can check the chip type, and the chip revision level, of everything in sight. (For you testability types: all ~260 chips have their pins, their control registers, and their signature analyzers, wired as a single board-level shift register. I believe that LSSD came out of Xerox, and signatures out of HP: thanks to them both.) -- Don D.C.Lindsay Carnegie Mellon School of Computer Science
BEAR@S34.Prime.COM (08/23/89)
Unless I'm mistaken, LSSD came out of IBM. -- Bob Beckwith Prime Computer, Inc. Internet: bear@s34.prime.com