Filename: FORCEDX4.TXT
WWW URL: http://www.firmware.com/support/bios/forcedx4.htm
FTP URL: ftp://ftp.firmware.com/text/forcedx4.txt
Revision: 06/17/96 TLS Micro Firmware Technical Support
Summary: Fix for some Phoenix BIOSes not correctly identifying early
versions of Intel 486DX4-100 ODP CPUs.
Phoenix 4.x code does not normally enable the internal CPU cache unless it can identify the CPU on bootup.
Some versions of some Phoenix 4.x BIOSes, including some Micro Firmware upgrades, may not recognize early versions of the Intel 486DX4 Overdrive (ODP or ODPR) and therefore may not enable the internal CPU cache. This is due to the fact that when Intel originally released the 486DX4 ODP CPUs, they used a new internal ID. They later changed this ID to the same as that for the 486DX4.
This DEBUG script will force a Phoenix 4.x BIOS to recognize a DX4 Overdrive CPU. It is actually programming CMOS RAM to set the CPU type to a 486DX4, which will cause the BIOS to enable the internal CPU cache. This must be rerun if CMOS RAM is lost.
C:\>DEBUG
- o 70 34
- o 71 E4
- q (quits to DOS prompt)
C:\>
Note - You must reboot system after running above script for it take effect.