Technical information

NewBIOS Reference Serial Solutions
Chapter 5
NewBIOS Reference.
Introduction.____________
This Chapter lists all the services provided by NewBIOS in
order of service number. For each service the following are
noted: its compatibility with the ROM BIOS, parameters, return
values, meaning and other points.
Where a service differs from an IBM equivalent the Serial
Solutions version is described, and the differences to the IBM
version noted.
The explanations supplied refer to the 16450, the serial
communications chip used in PC compatibles. The 16450 is a
higher specification version of the older 8250. Most modern 486
and Pentiums use the 16550 chip, this is an enhanced 16450
chip. Serial Solutions automatically detects and uses the
enhanced features of the 16550 serial port chip when it is
present in the PC.
Many BIOS services do little more than read from and
write to the 16450, so the reader may wish to refer to the
National Semi-conductor data sheet for the chip or to a serial
communications text which covers the 16450/16550 series.
Using The Services._________________
The services all switch to an internal stack when called, so
only require eight bytes of user stack space, including the six
bytes used by INT 14H and IRET.
All registers are preserved across the call, except those
which it is explicitly stated are used to return values after the
call. Only the registers AX, BX, CX, and DX, are used to
communicate with the calls, so it can be assumed that BP, DI,
SI, the segment registers and the flags will not be affected by
calling NewBIOS.
Chapter 5 Page 69