User`s manual

Card Setup
Address and IRQ selection
The COMHP 7804 is automatically assigned I/O addresses and IRQs by your motherboard BIOS or by a
‘Plug-n-Play’ Operating System. Adding or removing other hardware or moving the adapter to another slot may
change the assignment of I/O addresses and IRQs.
Clock Modes
The COMHP 7804 employs a unique clocking option that allows the end user to select from divide by 8 and
divide by 1 clocking modes. This mode is selected at S9.
To select the Baud rates commonly associated with COM: ports (i.e. 2400, 4800, 9600, 19.2,…115.2K Bps) place
the switch to the divide by 8 (Silkscreen - D8). In this mode the standard 14.7456 MHz oscillator is divided by 8
resulting in 1.8432Mhz, which provides standard COM: port frequencies.
To select the higher data rates place the switch to the divide by 1 (Silkscreen – D1). In this position all data rates
are 8 times the configured rate.
Baud Rates and Oscillator value
The following table shows some common data rates and the rates you should choose to achieve them when using
the COMHP 7804 in the D1 mode. If the O/S of choice is Windows 95/98/ME/2000/NT/XP, the
oscillator value (14.7456 MHz) should entered into the ‘Advanced Tab’ on 95/98/Me/2000/XP Device Manager
applet. When using Windows NT, the ‘Advanced Ports’ applet in the Control Panel should be launched and the
oscillator value may be entered in the ‘Advanced’ tab. When using any other OS (i.e. Linux, or QNX) the following
tables should be used.
For this Data Rate Choose this Data Rate
1200 bps 150 bps
2400 bps 300 bps
4800 bps 600 bps
9600 bps 1200 bps
19.2K bps 2400 bps
57.6 K bps 4800 bps
115.2 K bps 14.4K bps
230.4K bps 28.8K bps
460.8K bps 57.6 K bps
921.6K bps 115.2 K bps
If your communications package allows the use of Baud rate divisors, choose the appropriate divisor from the
following table:
For this Data Rate Choose this Divisor
1200 bps 768
2400 bps 384
4800 bps 192
9600 bps 96
19.2K bps 48
38.4K bps 24
57.6K bps 12
115.2K bps 8
230.4K bps 4
460.8K bps 2
921.6K bps 1
CyberResearch
®
Serial Communications COMHP 7804
CyberResearch, Inc. 2
25 Business Park Drive P: [phone]; F: [phone]
Branford, CT USA
www.cyberresearch.com