Ampro Corporation 486E - Manual (Page 35)

Product Reference
2–19
Note
Some programs that emulate an ASCII terminal do not properly
support the basic ASCII command functions shown in Table 2–14.
Ampro provides a suitable PC terminal emulator program, TVTERM,
on the Common Utilities diskette.
The keyboard and screen of the terminal become the system console after system boots. Programs
used this way must use ROM BIOS video functions rather than direct screen addressing for their
display I/O. Keyboard data from both the external serial device and the standard AT keyboard can
be entered.
Note
DOS programs that write directly to video RAM do not display
properly on a serial console device.
COM Port Table
When the system boots DOS initializes the serial ports to 9600 baud (typical). To preserve the
selected console port parameters stored in SETUP, the ROM BIOS can be instructed to delete the
selected console port from the internal COM port table, normally used by DOS to locate the serial
ports. With the port deleted from the COM port table, DOS cannot change its parameters. If you
use a serial console, be sure to select the option that deletes the console port from the COM port
table.
Serial Handshake
The serial console device data format and the Little Board/486e CPU serial port data format must
match for the devices to properly communicate. In addition, the hardware handshake behavior
must be compatible. Normally, a serial port’s Data Set Ready (DSR) and Clear To Send (CTS) input
handshake signals must be true (active) for the ROM BIOS to send data out. On the
Little Board/486e CPU, the hardware handshake can be enabled or disabled with SETUP. When
hardware handshaking is enabled, be sure to connect the DSR and CTS signals to appropriate
handshake signals on the external serial device’s interface connector. As an alternative, loop the
Little Board/486e CPU’s serial output handshake signals to its input signals as follows:
! DTR (out) to DSR (in)
! RTS (out) to CTS (in)