B&B Electronics PC Watchdog Timer Card ATRWDT - Manual (Page 20)

Documentation Number ATxWDT-1303 Appendix A A-1
B&B Electronics Mfg Co – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
B&B Electronics Ltd – Westlink Comm. Pk – Oranmore, Galway, Ireland – Ph +353 91-792444 – Fax +353 91-792445
Appendix A: Hardware I/O Maps
I/O Map of XT Class Machines
Hex Address Address Function in XT Class Machines
000-00F DMA controller (8237A)
020-021 Interrupt controller (8259A)
040-043 timer (8253)
060-063 PPI(8255A)
080-083 DMA page register (74LS612)
0A0-0AF NMI – non maskable interrupt
200-20F game port joystick controller
210-217 Expansion unit
2E8-2EF COM4 serial port
2F8-2FF COM2 serial port
300-31F Prototype card
320-32F hard disk
378-37F Parallel print
380-38F SDLC
3B0-3BF MDA - monochrome adapter and printer
3D0-3D7 CGA - color graphics adapter
3E8-3EF COM3 serial port
3F0-3F7 floppy diskette controller
3F8-3FF COM1 serial port