x86 Real Mode Legacy
Cluster focuses on the continued support for real mode, VM86, unreal mode, and legacy BIOS boot processes in modern x86 processors and PCs, including discussions on interrupts, A20 line, and compatibility with ancient hardware.
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You mean, like booting in real mode was codified for x86?
Someone please try this on an original (early 1980s) IBM-PC BIOS.
If one called INT-18 today, would we hit a similar stub in a modern PC BIOS?
No, it's all in 32-bit protected mode.
I think you're talking about unreal mode.http://wiki.osdev.org/Unreal_Mode
The IRQ remapping / A20 / segmented memory happened years before the AMD benchmarking / Dell payouts / etc.
8086 (and any subsequent intel chip, running in real mode)
Modern processors still know how to run 16 bit code.
Sure it does. All x86 CPUs boot up in real mode, for example. Bootloaders are written in real mode.
I'm talking about the firmware on the motherboard. Your BIOS is CPU-specific - if a future CPU changes the default CPU mode, you simply update your BIOS code to match while you're doing the rest of the work you need to do for that BIOS to run on the new CPU. If the BIOS expects to run in real mode (I'm not aware of any modern firmware that does, but) then you just add some code to switch back to real mode. Otherwise, you probably just delete the code that currently transitions fro