[comp.sys.ibm.pc] IBM Ports

alexhagn@neabbs.UUCP (ALEXANDER HAGEN) (04/12/90)

A few weeks ago, I heard about ports in the IBM PC, accessible by the IN
and OUT instructions of the 8088 - Yes, I own a XT. What I'm looking for
now are the addresses of these ports. Some of them I have found already:

     Clock            0040 - 0043
     Keyboard         0060 - 0063
     LPT2             0278 - 027F
     COM4             02E8 - 02EF
     COM2             02F8 - 02FF
     Harddisk         0320 - 032F
     LPT1             0378 - 037F
     MDA              0380 - 03BF
     CGA              03D0 - 03DF
     COM3             03E8 - 03EF
     Floppydisk       03F0 - 03F7
     COM1             03F8 - 03FF

As you might have seen, there are still some gaps. Perhaps you could fill
them in for me?

Although I do not intend to program these ports directly (at least not for
now), I tried to understand them, so I looked for them in RAM. My XT told
me that COM1 is located at address 03F8. However, I am told a PC address
consists of 5 digits, so I think I am missing one (or not?).

So, who can tell me where I can find the ports? Also, I would like to know
what registers in what ports have what functions. I have them for the
serial port, but all others are missing.

I would be very grateful if you could answer these questions (although they
probably mean a lot of work).

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