Flash Rom; System Controller Function - Acer Extensa 900 Series Maintenance Manual

4.2.2.2 Flash ROM

All versions of the Extensa notebook family use a "Flash" ROM that contains both the
main system BIOS and the VGA BIOS. The Flash ROM contains "Boot Block" logic that
allows downloading new versions of BIOS without destroying the Boot Load area.
The Flash ROM execution is 8 bits wide. However, better performance can be attained
by enabling the Shadow ROM in the CMOS setup routine or by selecting the Windows
Control Panel Applet. When the Shadow ROM is enabled, BIOS is copied into a 32-bit,
high-speed system.

4.2.3 System Controller Function

The Extensa 900 Series notebook design uses two chips, the ALI M1521 (memory, Cache
and DRAM Controller for the Pentium System and the M1523 (PCI to ISA Bridge chip)
combine to provide the 586 system controller function for the new multimedia/
multithreading operating system, Windows 95.
The notebook utilizes the BGA package to improve the AC characterization, resolves
system bottleneck and make the system manufacturing easier. The system architecture
includes the UMA, ECC, PBSRAM, SDRAM/BEDO, and multi-bus with highly efficient,
deep FIFO between the buses, such as the HOST/PCI/ISA dedicated IDE bus.
The I/O Address Map for the 900 Series Notebook is provided in Table 4-4.
4-6 Theory of Operation