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Basic Disk Operating System (BDOS) Functions
where:
dmaad = current user DMA address
dmabase= current user DMA base
curdsk = current user disk, 0-15 (A-P)
usrcode = current user area, 0-15
control_pJlag, 0 means do not echo console output to the printer. FF
means echo to the printer.
DIRECT BIOS CALL
ENTRY
RETURN
CL: 32H
FUNCTION 50
AH: Keyboard Input
Status
DX: BIOS
Descriptor
Offset
DIRECT BIOS CALL
or
(no value)
The Direct BIOS Call function provides a direct BIOS call and transfers control
through the BDOS to the BIOS. The DX register addresses a five-byte memory area
containing the BIOS call parameters:
8-bit
16-bit
16-bit
Func
value (CX)
value (DX)
]
where Func is a BIOS function number (see Table 5-1), and value (CX) and value
(DX) are the 16-bit values which would normally be passed directly in the CX and
DX registers with the BIOS call. The ex and DX values are loaded into the 8086
registers before the BIOS call is initiated.
NOTE
If the eON IN BIOS subroutine is called by this
function, the keyboard input status signal is
returned in register AH, indicating which latch
key (GRPH1, GRPH2, ALT, etc.) is pressed.
(See Appendix E, Keyboard Input Status.)
4-31
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