6-5
System Resources
• Check Point List 
POST (hex)  Description 
 CFh   Test CMOS R/W functionality. 
 C0h   Early chipset initialization: 
     -Disable shadow RAM 
     -Disable L2 cache (socket 7 or below) 
     -Program basic chipset registers 
 C1h   Detect memory 
     -Auto-detection of DRAM size, type and ECC. 
     -Auto-detection of L2 cache (socket 7 or below) 
A1h  Set Initial Conditions (Default Values) in EBP 
A2h  Determine FSB frequency. 
A3h  Begin Detection of installed DIMMS 
A4h  Check for Column Latency 
A5h  200Mhz or 266Mhz 
A6h  Check for tRAS timing 
A7h  Check for tRP timing 
A8h  Check for tRCD timing 
A9h  Check for ECC Support 
AAh  Check for refresh timing 
ABh  Verify that the DIMM's are in matched pairs 
 C3h   Expand compressed BIOS code to DRAM 
 C5h   Call chipset hook to copy BIOS back to E000 & F000 shadow 
 RAM. 
 01h   Expand the Xgroup codes locating in physical address 1000:0 
 02h   Reserved 
 03h   Initial Superio_Early_Init switch. 
 04h   Reserved 
 05h   1. Blank out screen 
 2. Clear CMOS error flag 
 06h   Reserved 
 07h   1. Clear 8042 interface 
 2. Initialize 8042 self-test 
 08h  1.  Test special keyboard controller for Winbond 977 series Super 
   I/O chips. 
2.  Enable keyboard interface. 
 09h   Reserved 
 0Ah  1. Disable PS/2 mouse interface (optional). 
2. Auto detect ports for keyboard & mouse followed by a port & interface swap 
(optional). 
3. Reset keyboard for Winbond 977 series Super I/O chips. 
 0Bh   Reserved 
 0Ch   Reserved 
 0Dh   Reserved 
 0Eh   Test F000h segment shadow to see whether it is R/W-able or not. If 
 test fails, keep beeping the speaker. 
 0Fh   Reserved