Hardware Reference
In-Depth Information
example of running the program is shown below. The program has been used
to display the contents of 10 bytes of RAM from address 0410 onwards:
Start address (in hex.)?
410
Number of bytes to display?
10
Address (hex.)
Byte (hex.)
410
63
411
44
412
BF
413
80
414
2
415
0
416
18
417
20
418
0
419
0
Unfortunately, the above information is not particularly useful unless you
know how each of the bytes is constructed and what the data actually represents!
Despite this, it is possible to interrogate the BIOS data area with simple software
in order, for example, to display the port addresses used on a system Table 1.14.
The PowerBASIC 3.5 program (available for downloading from the companion
web site) shows how the BIOS data area can be accessed and useful information
extracted from it. The result of running the program is shown in Figure 1.20.
' Name: biosdata.bas
Version: 0.5
Modified: 25/08/04
' Language: PowerBASIC 3.5
' Function: Display BIOS data
'
' Initialise
'
dim high as integer
dim low as integer
division$ = String$(40, Chr$(205))
Color 15, 1
Cls
'
' Get equipment list word at offset &H10
'
Def Seg = &H40
high% = peekl(&H10) \ 256
' low byte
low% = peekl(&H10) MOD 256
' high byte
'
' Print title and version number
'
print division$
print "BIOS Data 0.5"
'
' Get BIOS date
'
