Cyrix MediaGXm

DOS & Win9x
I use a combination of programs to enable FP_FAST, RSTK_EN, and LOOP_EN. The first program was in a zip file called CyrixGo.zip. It contains set5x86.exe and free5x86.exe and mentions the author as AEB Software. First run set5x86.exe. It goes through a series of questions concerning which Cyrix 5x86 features you would like enabled. Answer the questions as follows: LSSER = No, LOOP_EN = Yes, BTB_EN = No, RSTK_EN = Yes, BWRT = Yes, WT1 = Yes, USE_WBAK = Yes, DTE_EN = Yes, MEM_BYP = Yes. Unfortunately, there is no FP_FAST option to enable with this program and the program also makes a mess of many other register settings. This program creates a configuration file, 5x86.cfg which is invoked by free5x86.exe.

Place free5x86.exe in autoexec.bat

We now must use 6x86ctl.exe by Ray Van Tassle to fix the mess that free5x86.exe made and to enable FP_FAST. Unfortunately, 6x86ctl.exe does not allow for setting LOOP_EN and RSTK_EN, which is why free5x86.exe was required.

Place the following commands in your autoexec.bat

6x86ctl.exe -n1 -b2
6x86ctl.exe -n2 -b80
6x86ctl.exe -n2 -b8
6x86ctl.exe -n3 -b4
6x86ctl.exe -n4 -b80
6x86ctl.exe -n4 -b20 <------------this particular line enables FP_FAST

It was quite a headache to figure all this out. Unfortuneately, free5x86.exe leaves the colour of your DOS font as a reddish pink. Add mode co80 to your autoexec.bat file to bring the colour back to system default. Thanks to Malvineous for this tip.