rkc@XN.LL.MIT.EDU (rkc) (03/29/89)
> mahar@weitek.UUCP (Mike Mahar) says: > They [XL chipset] are used in imbedded systems mostly so they don't have much impact > on the UNIX world. It is popular with computer graphics people and it is the ... Part of the reason the XL chips haven't affected the UNIX world is because the chips don't correctly separate User and Supervisor Mode. The "backing registers" that are reserved for supervisor mode use can be accessed from user mode. Weitek's Support Staff currently suggests that application users be given assembly manuals with the man page for the SWAP instruction (which accesses those registers) removed. The chips are quite fast; but this is a big flaw. -Rob PS. Don't read this if you're an applications programmer for these chips.