Table 3. Frequently Unused Port Addresses
Base
Hex
Address
200
208
300
308
310
318
380
388
3A0
3A8
Binary
Equivalent
1000000000
1000001000
1100000000
1100001000
1100010000
1100011000
1110000000
1110001000
1110100000
1110101000
Switch Settings
MSB LSB
7654321
1000000
1000001
1100000
1100001
1100010
1100011
1110000
1110001
1110100
1110101
I/O Space
Description
game port
game port
prototype
prototype
prototype
prototype
SDLC
SDLC
bisync com
bisync com
Interrupt Jumper Setup
The IRQ is a hardware Interrupt Request line in an ISA bus expansion slot on a PC or AT compatible computer. The 8 bit PC ISA slot has 8 interrupts, the 16 bit slot has another 7 since one of the first 8 is used to link in the remaining 8. The IRQ is used by devices to request immediate service by the main microprocessor. When the IRQ line is set, the microprocessor stops whatever it’s doing, saves status, checks which line was set, then jumps to code to handle the interrupt. The processor then clears the interrupt and returns to what it was doing before. IRQ lines are set by the internal timer, keyboard, hard drive controller, PCI, USB controller, sound card, serial ports, printer and more.
The 3PXCC4A cards allow the use of interrupts (IRQ) 2, 3, 4, 5, 6, 7, 10, 11, 12, 14, and 15. Table 4 shows the standard serial port IRQ settings. Note: If two ports use the same IRQ setting, both ports cannot use the serial port at once. Only one port at a time may communicate.
Table 4. Standard IRQ Settings
COM1
COM2
COM3
COM4
IRQ4
IRQ3
IRQ4
IRQ3
34 | Manual Document# 3PXCC4A3001 |
B&B Electronics Mfg Co – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph
