Appendix A: Hardware I/O Map

Hex Address

000-00F

020-021

040-043

060-063

080-083

0A0-0AF

200-20F

210-217

2E8-2EF

2F8-2FF

300-31F

320-32F

378-37F

380-38F

3B0-3BF

3D0-3D7

3E8-3EF

3F0-3F7

3F8-3FF

I/O Map of XT Class Machines

Address Function in XT Class Machines

DMA controller (8237A)

interrupt controller (8259A)

timer (8253)

PPI(8255A)

DMA page register (74LS612)

NMI - non maskable interrupt

game port joystick controller

expansion unit

COM4 serial port

COM2 serial port

prototype card

hard disk

parallel print

SDLC

MDA - monochrome adapter and printer

CGA - color graphics adapter

COM3 serial port

floppy diskette controller

COM1 serial port

Manual Document# 3PXCC4A3001

Appendix A: Hardware I/O 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

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B&B Electronics 3PXCC4A manual Appendix a Hardware I/O Map