V5C Technical Manual
6-2
SBS Embedded Computers has implemented the Award ROM BIOS for complete
compatibility with IBM’s BIOS, without infringing on IBM’s copyright. Since
the BIOS is completely compatible in operation with the original, you can rest
assured that programs developed correctly will run, unmodified on the V5C.
In order to use the routines contained in the AT ROM BIOS, you will need to
know how to make BIOS calls through software interrupts. This is described in
detail in
Advanced MS-DOS
.
The NS16450/16550-compatible UART serial controllers within the
ALI 1543C Southbridge chip fully implement both the standard PC/AT COM1
and COM2 serial ports. These devices normally appear at the standard address-
es of 3F8H–3FFH for COM1 and 2F8H–2FFH for COM2. These addresses are
software configurable. Standard input and output with the COM ports is accom-
plished with BIOS calls through interrupt 14H. These calls are fully described
in Section 3 of Advanced MS-DOS.
The V5C incorporates a COM2 with additional functionality. COM2 can be
configured for an RS-232, RS-422, or RS-485 driver type. The COM2 driver
type can be configured in the Setup utility, as well as by using bit 7 of the Serial
Switch (See Serial Switch below).
WARNING:
Be sure that the type of driver selected matches the type of actual
connection. The differences in driver voltages and currents between the driver
types may cause damage to a connection of a different driver type. Changing the
COM2 configuration while the COM2 port has a connection is not recommended.
The parallel port is also provided by the ALI 1543C and is typically used for
interfacing to Centronics-compatible parallel printers. MS-DOS defines the
device, PRN, as the normal printer output device of the system. Therefore, the
programmer should not require access to the parallel port directly. Rather, print-
er services available through the AT BIOS at interrupt 17H should be used. AT
BIOS services are fully described in Section 3 of Advanced MS-DOS. Also, be
aware that the parallel port of the V5C is capable of SPP, ECP and EPP modes.
The ALI 1543C Southbridge has built-in PS2/AT Keyboard and PS2 Mouse
Controllers. Built into the AT BIOS are calls for keyboard services using inter-
rupt 16H. Section 3 of Advanced MS-DOS describes these calls in detail.
The Real-Time Clock of the V5C is equivalent to the Motorola 146818A and is
contained in the DS12887 IC. The RTC occupies 3FH indexed locations and
contains registers for clock timekeeping and control, as well as 16 bytes of
scratchpad RAM (reserved for use by AT Setup). As long as battery power is
provided, the clock will continue updating the date and time registers as well as
preserve the contents of the scratchpad RAM.
Serial Communications
Interface
Parallel Port
Keyboard/Mouse Port
Real Time Clock
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