DIGITAL-LOGIC MICROSPACE MSEP800, Technical User'S Manual

Page: 116 / 140

DIGITAL-LOGIC AG
MSEP800 Manual V1.0G
116
14 D
IAGNOSTICS
14.1 POST CODES
This is the GeodeRom port 80 flow for a cold boot on a gx system. There are some additional codes on a
scx2xx system. This shows what functions generate which port 80 code. The first column of codes are
generated by xpresrom.asm the second column is the function which is run after the post code and any
additional post codes generated by that function.
BIOS POST CODES
Checkpoint Function Name Intermediate
Codes
Function Description
FOh Reset Vector FOh XpressROM code execution start
80h UserPrelnit --- User added code to be run first
00h PreSiolnit 60h First SIO access, Core SIO initialize, LPT can be
mapped to 1/0 80h for
embedded devices to provide POST code output.
01h Clocklnit --- Chipset level clock initialize
02h GxmReglnit --- 1/0 based Geode initialize
03h UnReal --- Create a 32-bit real mode descriptor
04h gxmMemReg1nit --- Memory mapped 1/0 based Geode initialize
05h gxmTest --- Geode CPU tests
20h Test entry
28h- 2Fh Test stepping ID (2Fh = Test Failed)
2Ah Test feature
2Eh Test passed exit
06h MemSetup --- Auto size memory controller DIMM I and DIMMO
70h Set the clock drive strength and shift value, mask the
clocks
72h Set the data, address, and control drive, clear
reference timer and VGA
wrap
73h Set the register to indicate no DIMMs installed
74h Default CAS latency to 3
75h or 7Fh Memory sizing (7Fh = No memory located)
76h Do refresh
7E MemSetup exit
memTestPinChec
k
--- See if MTEST pins to be enabled
07h memSetUpStack --- Setup a stack
90h or 9Fh Create stack (9Fh = Stack creation failure)
9Eh Stack setup exit
08h memTest --- Test memory address lines
BOh Test memory
BEh Memory test exit
BFh Memory test failed (i.e., BOh)
09h shadowRom --- Copy ROM from FOOO:0000 to RAM at FOOO:0000