Ampro Corporation COM 830 manual System Resources, Address Assignment, System Memory Map, Bios

Chapter 3 Signals and Pinout Tables

CAUTION The signals listed in the table above are used as chipset configuration straps during system reset. In this condition (during reset), they are inputs that are pulled to the correct state by either COM Express internally implemented resistors or chipset internally implemented resistors that are located on the module. No external DC loads or external pull-up or pull-down resistors should change the configuration of the signals listed in the above table with the exception of AC_SYNC and AC_SDOUT. External resistors may override the internal strap states and cause the COM Express module to malfunction and/or cause irreparable damage to the module.

AC_SYNC and AC_SDOUT can be used to switch PCI Express channels 1-4 between x1 and x4 mode. If both signals are each pulled-up (using 1K resistors) to 3.3V at the rising edge of PWROK then x4 mode is enabled. x1 mode is used by default if these resistors are not populated.

System Resources

System Memory Map

Table 3-25. Memory Map

Address Range (decimal)	Address Range (hex)	Size	Description
(TOM-192kB) – TOM	N.A.	192kB	ACPI reclaim, MPS
			and NVS area **
(TOM-8MB-192kB) – (TOM-	N.A.	1 or 8MB	VGA frame buffer *
192kB)
1024kB – (TOM-8MB-192kB)	100000 – N.A	N.A.	Extended memory
869kB – 1024kB	E0000 - FFFFF	128kB	Runtime BIOS
832kB – 869kB	D0000 - DFFFF	64kB	Upper memory
640kB – 832kB	A0000 - CFFFF	192kB	Video memory and
			BIOS
639kB – 640kB	9FC00 - 9FFFF	1kB	Extended BIOS data
0 – 639kB	00000 - 9FC00	512kB	Conventional memory

NOTE T.O.M. = Top of memory = max. DRAM installed

*VGA frame buffer can be reduced to 1MB in setup. ** Only if ACPI Aware OS is set to YES in setup

I/O Address Assignment

The I/O address assignment of the COM 830 module is functionally identical with a standard PC/AT. The most important addresses and the ones that differ from the standard PC/AT configuration are listed in the table below.

46 Reference Manual COM 830