That appears to be the same Kingston driver file I also have. I bet there was only one revision.
I have taken some time to analyse your comments concerning the LGHT486 vs. REVTO486 drivers. I have updated my thread concerning various CPU processor register settings, Register settings for various CPUs
In short, the Kingston driver has a non-optimal FPU setting which showed a marked reduction in performance, at least in Landmark Speed test. On the flip side, the Kingston driver has confirmed my suspicion, that XTOUT = 0 . This is the source of your increased performance from DOOM using the Kingston driver. There's one other notable setting difference, that is, disabling L1 while not in use. Kingston does this by default, which costs 4 realtics in DOOM, but since we are overclocking these rare processors, I think it might be the preferred setting. My full diagnosis is as follows.
The Evergreen driver and the Kingston driver setup the register a little differently. The most notable concerning performance are:
Processor Operation Register, Byte 1, or 1000h:1
Bit 7, CNPX - REVTO486 sets as 1, while LGHT486 sets to 0. The optimal setting is 1. Setting it to 0 drops FPU performance, as witnessed in Landmark Speed from 224.8 to 203.9
Bit 4, XTOUT - REVTO486 sets as 1, while LGHT486 sets as 0. The optimal setting is 0. Setting it to 1 drops DOOM score by 49 realtics.
These two settings can be set optimal using CTCHIP34. The command line option for this would be:
CTCHIP34 IBM486 /1000h:1:=%1xx0xxxx
If you are wanting to place this in autoexec.bat, you need an extra %, that is:
CTCHIP34 IBM486 /1000h:1:=%%1xx0xxxx
If for some reason, it is still not working correctly with autoexec.bat, use HEX syntax (but cannot set don't care's):
CTCHIP34 IBM486 /1000h:1:=8C
Processor Control Register, Byte 3, or 1000h:3
Bit 4, CLP - REVTO486 sets as 0, while LGHT486 sets as 1. Setting this to 1 lets the L1 cache turn off while not in use to save power, but doing so drops 4 realtics in DOOM. However, if you are overclocking your CPU, and given the rarity of these chips now, it may be more beneficial to turn L1 off while not in use.
If you want to force disable of L1 power savings, use CTCHIP34 IBM486 /1004h:3:=00
If you want to force enable of L1 power savings, use CTCHIP34 IBM486 /1004h:3:=10
Many systems have trouble with the IBM Blue Lightning BL2/BL3/DLC3 chip. Use HIMEM with /TESTMEM:on for an initial test. The following HIMEM settings have helped the BL3 work on many of my systems,
/MACHINE:1
/CPUCLOCK:ON
e.g. in config.sys, DEVICE=HIMEM.SYS /TESTMEM:on /CPUCLOCK:on /MACHINE:1 /V
The best outcome appears to be loading the REVTO486.SYS or LGHT486.SYS right before HIMEM, however this may lead to a HIMEM error. On my SiS Rabbit system, I have thus set /TESTMEM:off and have not witnessed any issues in DOS or Windows 3.11
You can also load REVTO486.SYS after HIMEM, but for applications in DOS/WIN311 to run properly, I have had to set DOS=UMB in config.sys rather than DOS=HIGH,UMB. Thanks to user pshipkov for this hint.
There are also some slight differences between REVTO486.sys and LGHT486.sys which I have not noticed any performance differences. These are as follows.
Processor Operation Register, Byte 0 or 1000h:0
Bit 6, DBCS, Cache Double Byte Character Set. REVTO486.sys sets this to 0, while LGHT486.sys sets to 1
Bit 1, CPC, Cache Parity Checking. REVTO486.SYS sets to 1, while LGHT486.sys sets to 0
Cache Region Control Register, Byte 3, or 1001h:3
Bits 7-0, LMROR, 1 Meg Read only hi-byte. REVTO486.sys sets this to 00000000, while LGHT486.sys sets to 00010000
Cache Region Control Register, Byte 1, or 1001h:1
Bits 7-9, LMCR, 1 Meg Cacheable hi-byte. REVTO486.sys sets this to 00000011, while LGHT486.sys sets to 00010011
Plan your life wisely, you'll be dead before you know it.