Dell OptiPlex G1 - Manual (Page 16)

I/O Map: Dell ™ OptiPlex ™ G1 Systems
Address Device
0000–000F DMA controller #1
0020–003F Interrupt controller #1
0040–0043 System timers
0044–005F Reserved
0060–006F Keyboard controller
0070–0071 RTC and NMI enable
0080–008F DMA page registers
00A0–00BF Interrupt controller #2
00C0–00DF DMA controller #2
00F0 Coprocessor busy clear
00F1 Coprocessor busy reset
00F2–00FF Available
278–27F LPT2
2E8–2EF COM4
2F8–2FF COM2
378–37F LPT1
3E8–3EF COM3
3F8–3FF COM1