Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!sdd.hp.com!spool.mu.edu!uwm.edu!psuvax1!ukma!seismo!dimacs.rutgers.edu!rutgers!cbmvax!brim From: brim@cbmvax.commodore.com (Mike Brim - Product Assurance) Newsgroups: comp.sys.ibm.pc.hardware Subject: Re: The Case of the Phantom 80287... Keywords: Works but can't detect it! Message-ID: <19991@cbmvax.commodore.com> Date: 20 Mar 91 13:36:46 GMT References: <1991Mar18.165314.5994@uncecs.edu> Reply-To: brim@cbmvax.commodore.com (Mike Brim - Product Assurance) Organization: Commodore, West Chester, PA Lines: 57 In article <1991Mar18.165314.5994@uncecs.edu> cjl@uncecs.edu (Charles J. Lord) writes: > > I have two 8Mhz AT 'clones' that both have a strange problem. > Both have had '287s in them from the beginning (3-4 years), but > recently Norton's SI and a few programs can't detect the coprocessor. > It passes the 87test on wuarchive, runs autosketch, QB87, etc but > won't run a commercial program from Data Translation (compiled in > God knows what) with an error (FP not installed). CMOS shows > "coprocessor installed". I have switched from PCDOS3.1 to 3.3 in > the last six months and added a JDR-MCT secondary floppy controller > with 1.44MB bios add-on - could either one of those changes have screwed > up the INT2 handling? It may be possible that the equipment byte 14 in the CMOS data area is set incorrectly. One of the bits tell if a math-co is present or not and some programs look here. I have seen this happen on a few systems that had a Phoenix BIOS. Also located in that byte is the number of floppies installed, so the addition of the floppy cont. MAY have changed both bits. Equipment Byte 14H Bit 7 - bit 6 Indicates the # of diskette drives installed: 00 1 drive 01 2 drives 10 reserved 11 reserved Bit 5 - bit 4 Primary display 00 EGA/VGA 01 40 column 10 80 column 11 Mono Bit 3 - bit 2 Not used Bit 1 Math-co presence bit: 0 math-co not installed 1 math-co installed Bit 0 Diskette drive presence bit: 0 diskette drive not installed 1 diskette drive installed Hope this helps. -- ******************************************************************************** Disclaimer: I don't speak for my company or myself. Mike Brim | Commodore Electronics Limited PC Analyst - System Evaluation Group | West Chester, PA 19380 Product Assurance | InterNet: brim@cbmvax.commodore.com ********************************************************************************