ErgoPro e-, x- and s- Series PC Specialist's Handbook
Page 58 First Edition, Release 4 - June 1998
2D Check for any parity error.
2E Disable parity checking. Port 61 = FC
2F Clear lower 64k of memory (Note: No test is performed). Restore ResetFlag (write to location 40:72).
Set up stack, SS:SP = 0000:0400. Set up interrupt vectors.
30 Checksum BIOS from F000:0000 to F000:FFFF.
31 Test KB-controller. In case of error, the emitted speaker error code gives detailed description of error
cause.
32 Enable address line A20.
33 Perform a function check of the CMOS cell 0F (Shut-down cause) by writing and reading a 1, 2, 4, 8
... When the walking one test is finished the contents of cell 0F is set to zero.
34 Check CMOS battery bit in cell 0D.
35 Write a CMOS default contents into the CMOS memory. This is the CMOS memory contents after
battery power has been removed.
36 Checksum the CMOS memory. This is done in two parts: One checksum for cells 10 to 2D is located
at 2E (msb) and 2F (lsb).
37 Check if CMOS memory is OK (Battery OK, Shut-down cell 0F OK and checksum OK). If good, set the
BIOS data area 'Equipment byte' and 'Memory size word' from CMOS cells 10 and 15, 16.
39 Initialize interrupt controllers (master and slave).Port20 = 11Port 21 = 08, 04, 01, FFPort A0 = 11Port
A1 = 70, 02, 01, FFPort 21 = Port 21 AND FB (Slave enabled)
3A Enable interrupt vectors.Vector 00 - 1F set to BIOS code/dataVector 20 - 5F set to Default_IntVector
60 - 66 set to 0000:0000Vector 67 - 6F set to Default_IntVector 70 - 77 set to BIOS code/dataFrom
now on processor interrupts are enabled.
3B Enable IRQ 0 (timer). Bit 0 of port 21 is cleared. From now on timer interrupts are running.
3C Determine CPU speed by comparing processor clock to timer clock (1.19MHz).
3D Test video type in CMOS configuration. If no video then next checkpoint is 41. If color video then next
checkpoint is 3F.
3E Test memory from B000:0000 to B000:7FFF with data 5555. If memory found then 'Equipment byte' is
modified and next checkpoint is 41.
3F Check color video memory (B800:0000 to B800:7FFF) with data 5555. If memory found then next
checkpoint is 41.
40 Test mono video memory with data is 5555. If memory is OK then next checkpoint is 41. No other
video memory found. Modify 'Equipment byte'.
41 Scan for video adapter PROM from C000:0000 to C800:0000.Initialize video card and clear screen (A
lot of video I/O is done here).
42 Checksum video boards at C000:0000 to C800:0000 and call it to initialize itself.
47 Print power on message on screen.Read keyboard power on status at port 60.
48 DS458: Enable/Disable Unix mode according to CMOS.
50 DS458: EISA Configuration.
51 Clear 640k flag (bit 8) in CMOS cell 33.
52 Scan base memory starting at 64k for end of memory. Pattern is 0000 and FFFF.
53 Check memory addressability by writing 1000 at 1000:0000, 2000 at 2000:0000 then 4000 at
4000:0000 and so on until end of base memory and then reading back and verifying. If memory is OK
then next checkpoint is 55.
54 Print error message on screen.
55 Check base memory data with patterns FFFF, AAAA, 5555, 0101 and 0000. Each 64k block tested is
verified with a message written on screen.
56 Compare memory size to what is specified in CMOS memory. Set 640k flag if 640k memory was
found.
57 Check extension memory. Enter protected mode.
59 Scan expansion memory until end is found. Data used is 0000 and FFFF.
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