Specifications

Command Descriptions 95
Parameter ('P','p')
Function: Changes controller communication parameters.
When the parameters are set with this command, the Acknowledge packet is
returned using the new communication parameters. Therefore, the host
communication parameters must be changed immediately after issuing the
Parameter command.
The IO byte indicates the type of communication interface that is in use by the
controller as follows: an ASCII '0' for serial, '1' for PC-Bus, and '2' for Micro
Channel. The IO field cannot be changed.
PC-Bus and Micro Channel Controllers
The Bus1 byte specifies the Interrupt number (IRQ) to use for bus
communications. A value of zero indicates Polled Mode.
The Bus2 integer specifies the Base I/O Port address for the controller. The Base
I/O Port address is always on an 8 byte boundary.
The factory defaults for PC-Bus controllers when booting from NVRAM are Base
I/O Port 280h and no Interrupt (polled). These defaults may be overridden if the
controller boots from jumper settings.
The Base I/O Port and Interrupt for Micro Channel controllers are selected by the
System Configuration routine on the IBM Reference Disk.
Serial Controllers
The Ser1 byte has the following bit definitions:
Bit Description
0 Baud Rate (see table below)
1 Baud Rate (see table below)
2 Baud Rate (see table below)
3 0 = 8 bit data, 1 = 7 bit data
4 0 = 1 stop bit, 1 = 2 stop bits
5 1 = parity enabled as per bits 6 7
6 Parity Type (see table below)
7 Parity Type (see table below)
The Ser2 byte has the following bit definitions:
Bit Description
0 1 = Checksum required