Intermec PEN*KEY 6100, Руководство программиста

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SECTION 7 Reference, System Information
PEN*KEY
R
6100 Computer Programmer’s Reference Guide 7-11
BIOS/CMOS System Variables
ROM BIOS is system software at the lowest layer of a PC operating environĆ
ment. ROM BIOS provides a hardware abstraction level in a system so that
higher levels of software need not be concerned with certain hardware details.
Occasionally, it is helpful to examine the ROM BIOS or at least look at the data
that it uses to get its job done. The following are lists of data areas on which the
ROM BIOS operates.
"
NOTE: A full description of each variable used by BIOS is beyond the scope of this guide.
ROM BIOS Data Area
A PCĆcompatible ROM BIOS uses system variables stored, starting at location
40:0h. This address starts the first block of data immediately following the inĆ
terrupt vector table. A de facto industry standard defines most of the variables
on which a ROM BIOS must operate. In the following table, the entries unique
to the NORAND
R
BIOS are
italicized and bold
. The rest are defined in accorĆ
dance with the industry standard.
Table 7Ć7
BIOS Data in System RAM
Addr Size Description
40:00 4 words I/O address of up to four asynchronous communications adapters (COM1ćCOM4)
40:08 3 words Reserved: I/O address, up to 3 printer adapters (LPT1 LPT3)
40:0E word Segment address of extended BIOS Data Area
40:10 word Equipment status word (Returned by interrupt 11h)
40:12 byte Reserved: POST status
40:13 word Conventional memory size in kilobytes (returned by INT12h)
40:15 word
Pass/Fail indicators for RAM POST test
40:17 word Keyboard shift flags
40:19 byte AltĆkeypad accumulator
40:1A word Pointer to next keycode in keyboard buffer
40:1C word Pointer to next available location to save a keycode in the keyboard buffer
40:1E 16 words Circular keyboard buffer
40:3E byte Reserved: diskette recalibrate status
40:3F byte Reserved: diskette motor status
40:40 byte Reserved: diskette master timeĆout control
40:41 byte Diskette status return codeĊstatus of last RAM card access
40:42 7 bytes Reserved: diskette controller status bytes
40:49 byte Video mode setting
40:4A word Number of video columns in memoryĊnot all columns are represented onscreen
40:4C word Current page size (in bytes)
40:4E word Current page address
40:50 8 words Cursor position for each page
40:60 word Cursor display mode (start/end line)
40:62 byte Current display page
40:63 word I/O address of display hardware
40:65 byte Current mode select register
40:66 byte Current palette value
7. Reference,
System Information