Part Two - BIOS ROMs of the WYSE Sx0 - S50
The ROMs: VSA Init ROM: (Virtual Systems Architecture) is a piece of software that is hiding the real hardware from the OS and is emulating standard hardware like keyboard controller, IDE controller, CMOS and other legacy hardware. The Geode, rather than carrying lots of legacy hardware interfaces that are presumed to exist on x86 systems that might be painful to implement on a highly integrated, low power processor, the Geode often emulates such interfaces by use of software that is invoked by special traps that take place when the processor accesses these devices. This emulation is made at the hardware level by setting some Model Specific Registers (MSRs) that control the GeodeLink Interface Units (GLIUs). This GLIUs can trap CPU access to some defined memory regions and run some ISRs from VSA software instead, or route the access to some other devices. VSA system is a TSR software(Terminate and Stay Reside...