Subj : Interrupts To : Lee Aroner From : Jonathan de Boyne Pollard Date : Mon Jun 04 2001 01:17 am LA>> I had assumed that OS/2 used the same method of LA>> forcing a processor exception LA>> to jump to ring zero as MonopolySoft uses, apparently I was wrong. JdBP>> Strictly speaking, the design of OS/2 in this area is partly JdBP>> Microsoft's. LA> I guess that would tell us something about what G. Letwin thought LA> of the jump to the bios IBM copyright notice as a means of LA> switching processor state then, eh? That's not involved here, though. That particular mechanism was used, in OS/2 version 1.x, for switching from protected mode back to real mode in order to run DOS programs in the DOS box. Here, we are talking about the CPU remaining in protected mode, and simply switching from ring 3 to ring 0, which is what happens when a native OS/2 program calls into the kernel. ¯ JdeBP ® --- FleetStreet 1.22 NR * Origin: JdeBP's point, using Squish (2:257/609.3) .