B
System Resources
50
BIOS organization and system memory map
POST checkpoint codes
POST 80 codes
his section lists the POST checkpoint codes that the system BIOS may send to I/O port 80h
during POST. They are presented in an alphabetically ascending order and are not
necessarily in order of execution.
If an error occurs at any of the listed checkpoints, the system attempts to generate beeps
to indicate where the error occurred. To hear the beeps, connect a speaker (not included)
to the speaker pin on the front panel I/O header. Beep codes are derived from the
checkpoint code in the following way:
1. The 8-bit hexadecimal checkpoint code is converted to binary, then the binary number
is divided into four 2-bit groups. For example:
Checkpoint code 20h = 00100000 = 00-10-00-00
2. Each 2-bit group is converted to a one-based number, and 1 is added to indicate the
number of beeps:
3. 00 10 00 00 = 1-3-1-1 beeps
Note:
Only standard Phoenix TrustedCore BIOS POST 80 codes are listed in the tables
below. If you encounter other POST 80 codes, contact RadiSys for further assistance.
Range
Description
Cacheable
0 to 640 KB
0000 0000
0009 FFFF
DOS compatibility area
Yes
640 KB to 1 MB
000A 0000
000B FFFF
Legacy video DRAM, mapped to the video
module (SMM memory) 128 K
No
000C 0000
000C BFFF
Write-protected DRAM containing
shadowed video BIOS (48 KB)
Yes
000D 0000
000D FFFF
BIOS extensions
Yes
1
1. If no BIOS extensions and ISA bus (aliased), not cacheable.
000E 0000
000F FFFF
System BIOS shadow
Yes
1 MB to 512 MB
0010 0000
0FFF FFFF
DRAM (511 MB)
Yes
2
2. If no DRAM and ISA bus (aliased), not cacheable.
512 MB to Top
1 MB
1000 0000
FFEF FFFF
ISA bus (aliased)
No
Top 1 MB
FFF0 0000
FFFF FFFF
System ROM (1MB flash boot device)
No
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from