MICROBEE PCFW-104 Bedienungsanleitung PDF herunterladen (Seite 6)

98, ME, NT, 2000 and XP may limit your IRQ selection without aftermarket drivers. This is

usually not required unless all IRQ’s supported by the OS are already allocated.

Note

PC/104 CPU manufacturers vary in implementation of the interrupt interface. Most use pull-

ups on the interrupts. This allows a board to drive low or tristate ﬂoat high the interrupt lines

preventing damage if two boards conﬂict. The PCFW-104 uses the tristate scheme. On a few

motherboards the manufacturers use pulldown resistors. The PCFW will not request a inter-

rupt in this scheme since the tristated line cannot ﬂoat high. In this case a pad is provided

for installation of a pullup resisitor, R8. The user should install a 1K 0805 resistor on this pad.

Should this not work the largest value possible should be used to prevent excessive current

draw. 250 ohms is a recommended minimum

Address Select Jumpers, JP2

For ﬂexibility with most SW and Development libraries this unit will support any valid address

between 0x000-0x007 and 0x7F8-0x7FF.

Most applications will use one of the common serial port addresses. The most common are:

COM1 = 3F8, IRQ4, COM2 = 2F8, IRQ3 COM3 = 3E8, IRQ4 COM4 = 2E8, IRQ3

Most software development libraries for serial communication support non-standard address

and/or IRQ assignments.

An excellent library is the COMM/DRV LIB from Willies Computer Software at http://www.

wcscnet.com/.

The default address is 3E8 which is COM3. To select the address you desire place jumpers on

JP2 in the following order.

From left to right. Placing a jumper sets the address bit to 0 or low.

Addressing Examples

Hex A10 A9 A8 A7 A6 A5 A4 A3

2F8 X X

300 X X X X X X

310 X X X X X

3E8 X X

3F8 X

7F8

X = jumper installed meaning bit = 0.

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MICROBEE PCFW-104 Bedienungsanleitung Seite 6