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From: TOMIII@MTUS5.BITNET (Thomas Dwyer III)
Newsgroups: comp.os.msdos.programmer,comp.sys.zenith,comp.sys.ibm.pc.misc
Subject: Programming the keyboard port
Message-ID: <90226.104110TOMIII@MTUS5.BITNET>
Date: 14 Aug 90 15:41:10 GMT
Organization: Computing Technology Services, Michigan Technological Univ.
Lines: 29

According to my "Z-386/AT Series Workstation Technical Reference
Manual, Volume II Programmable Registers" book, page 17-2 it says:

  The Status Register (Port 064H)

  The Status register is an 8-bit read-only register. [text ommited]


Now on page 17-3 it says:

  Command Register (Port 064H)

  The command register is an 8-bit write-only register, addressed at I/O
  port 064H. [text ommited]


Ok people, how can the same port be both read-only and write-only?  Am
I missing something?  Am I correct in thinking that if I write a SCP
command (page 17-5) to port 064H than I can read the results of the
command from port 060H?  My tests show that any value written to port
064H followed by a read of port 060H results in a 01CH being read.

Any help on this would be most appreciated.

Thanks,
Thomas Dwyer III                            TOMIII   @ MTUS5.BITNET
Network Programmer                          DWYERIII @ MTUS5.BITNET
Computing Technology Services
Michigan Technological University