Xref: utzoo alt.msdos.programmer:809 comp.sys.ibm.pc:39197 Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!samsung!usc!ucsd!ogccse!littlei!guardian!peter From: peter@guardian.UUCP (peter) Newsgroups: alt.msdos.programmer,comp.sys.ibm.pc Subject: Re: Precision control on an 80x87 Summary: Reserved in 80287, 80387, 80486 Message-ID: <308@guardian.UUCP> Date: 1 Dec 89 19:35:44 GMT References: <912@maytag.waterloo.edu> Reply-To: peter@langlab1.hf.intel.com (Peter Plamondon) Organization: Intel Development Tools Operation, Hillsboro OR Lines: 34 In article <912@maytag.waterloo.edu> dmurdoch@watstat.waterloo.edu (Duncan Murdoch) writes: | |I was just looking through the floating point code in a Turbo Pascal program, |and I see that at one point it sets the precision control bits to 01. My old |8087 manual lists codes | 00 - 24 bits | 01 - (reserved) | 10 - 53 bits | 11 - 64 bits |Does anyone know what setting it to 01 is supposed to do? Is it something new |on the 287, 387 or 486? | |Duncan Murdoch I looked through my collection of reference manuals and they all list 01 as reserved. Here's where I checked: 80286 and 80287 Programmer's Reference Manual, 210498-005 (1987) Figure 1-5, p1-12. (In the second section of the book!) 80387 Programmer's Reference Manual, 231917-001 (1987) Figure 2-3, p2-6. i486(tm) Microprocessor, 240440-001 (1989) Figure 2.14, p33. (bound, 175 page "data sheet") There must be something tricky going on. applies. ------------------------------------------------------------------------------- Peter Plamondon, Intel Corp, 5200 NE Elam Young Pkwy, Hillsboro, OR 97124-6497 Internet: peter@langlab1.hf.intel.com +1 503-696-5219 UUNET : uunet!intelhf!langlab1!peter "I speak for myself, as best I can." UUCP : tektronix!psueea!foobar!langlab1.hf.intel.com!peter -------------------------------------------------------------------------------