Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!oakhill!marvin From: marvin@oakhill.UUCP (Marvin Denman) Newsgroups: comp.sys.m88k Subject: Re: SERIALIZATION bit (was Re: WELCOME to comp.sys.m88k) Keywords: 88000 Message-ID: <2610@yogi.oakhill.UUCP> Date: 13 Nov 89 15:25:43 GMT References: <223@m1.UUCP> <1989Nov12.173826.19296@paris.ics.uci.edu> Reply-To: marvin@yogi.UUCP (Marvin Denman) Organization: Motorola Inc., Austin, Texas Lines: 37 In article <1989Nov12.173826.19296@paris.ics.uci.edu> Ron Guilmette writes: >OK. Here is a harder one. I noticed in the 88100 hardware manual that >there is a control bit (in one of the control registers) that is said to >be the "SERIALIZATION" bit. The manual (cryptically) sez that setting >this bit "serializes" the processor. This terse note then sez to "see >section so-and-so for further information". > >Well, I looked in section "so-and-so" (sorry, I don't have the book right >here just now) and guess what! There is *no mention* of the serialization >bit in there! What gives? The lack of discussion of the SERIALIZATION bit in the manual confuses me also. I have no excuses for the manual, but I will try to explain how it works. The serialization bit in the PSR causes all out standing operations to be completed before the next instruction is issued. This is identical to what happens when a tb1, tb0, tcnd, rte, or xmem instruction is issued except the serialization bit causes it to happen for all instructions. The processor will still prefetch the next instruction but will go no further in the instruction stream. >What I *really* want to know (besides *all* of the details) is whether >or not this bit could be useful to debuggers (i.e. does it disable the >otherwise confusing effects of pipelining). This bit is useful for debuggers if nothing else because it simplifies the problem greatly. My question is whether or not this bit belongs in the BCS. Right now it is one of the bits controllable from a user program. I realize its importance to debuggers, but is it really needed by applications programs. Marvin Denman Motorola 88000 Design -- Marvin Denman Motorola 88000 Design