Retro: When did flash ROM replace traditional ROM + CMOS chips?

[W Gruffydd]

In other words, when did motherboards start using flash ROM chips to hold both the system BIOS and the CMOS settings?

What were some of the first motherboards that used re-writable flash ROM chips, while ditching the CMOS chip entirely, or relegating the CMOS chip to just keep time?

If any assumptions in asking these questions are incorrect, I assume they will be pointed out posthaste.

 

[michalrz]

Could be wrong but it was always the case that the chip held both CMOS settings and the BIOS code. They were socketed, and the older ones has a small window for erasing using UV rays.

 

[W Gruffydd]

The ROM chip holding the system BIOS used to be read-only. It contained programs for talking to hardware that didn't change, such as the 8042 keyboard, motherboard chipset, and PC speaker. This necessitated a separate chip--the CMOS--for hardware likely to change, such as RAM, hard drives, and floppy drives.

The CMOS chip didn't store programs like the system ROM chip, just data that was read by the BIOS on the system ROM to complete programs needed to talk to changeable hardware. The BIOS routines for changeable hardware were still on the system ROM, but they could access parameters contained on the CMOS chip, parameters that could be modified to reflect changes in hardware.

That's my understanding, anyways.