First post, by mateusz.viste
mateusz.viste
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I have a 386SX that I use to test my software on. I've always wished to get some extra conventional memory by loading the DOS kernel and some TSRs high, but none of the UMB drivers I tested worked with the chipset of this mainboard, an UMC 82C336F chip codenamed "Twinstar".
Yesterday I dumped and dissassembled the BIOS of this PC so I could figure out how the BIOS configures the chipset's shadow RAM. Once I got it, I made a driver that allows to transform up to 64K of shadow RAM into UMBs. I published the result of this work today.
People having a mainboard based on the UMC UM82C33x "Twinstar" chipset can now enjoy some UMBs.