mikes@iuvax.cs.indiana.edu (Michael Squires) (01/18/91)
I had some problems with a 486/25 running under SCO ODT 1.0 that have been traced to improper setup. The board was (apparently) an MCT 486/25 baby AT with 8MB of DRAM using the OPTI chipset, AMI 486 BIOS. The system ran at about 1/3 the expected speed under UNIX but close to the expected speed under DOS. It turned out that the jumpers on the motherboard that enable/disable the external cache overrode the XCMOS setup and that the 8K on-chip cache was always enabled and its parameters were set by the other XCMOS settings. Changing the BIOS cache parameters to cache off and all 8MB cachable increased speeds from 6900 1.1 Dhrystones/sec to 21,000. (The XCMOS had arrived set for 1MB cachable, so the system cached for DOS but not for UNIX above 1MB of physical memory.) I tried the updated /boot from SCO but that had no effect one way or the other. Moral: get docs from your vendor on XCMOS setup if you intend to use a 486 with UNIX. Mike Squires (mikes@iuvax.cs.indiana.edu) 812 855 3974 (w) 812 333 6564 (h) mikes@iuvax.cs.indiana.edu 546 N Park Ridge Rd., Bloomington, IN 47408 Under construction: mikes@sir-alan.cica.indiana.edu -- Mike Squires (mikes@iuvax.cs.indiana.edu) 812 855 3974 (w) 812 333 6564 (h) mikes@iuvax.cs.indiana.edu 546 N Park Ridge Rd., Bloomington, IN 47408 Under construction: mikes@sir-alan.cica.indiana.edu