Article View: comp.os.msdos.programmer
Article #1952Re: Programming the keyboard port
From: Frank Zsitvay
Date: Sat, 18 Aug 1990 10:51
Date: Sat, 18 Aug 1990 10:51
31 lines
1466 bytes
1466 bytes
In article <90226.104110TOMIII@MTUS5.BITNET> TOMIII@MTUS5.BITNET (Thomas Dwyer III) writes: >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 When you write to port 064H you write to the command register. When you read from 064H, you read the status register, not the contents of the command register. zilog has been confusing programmers with this for years... -- fzsitvay@techbook.COM - one of these days i'll get it right... Version 2 of anything is usually the version that works.
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arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!zephyr.ens.tek.com!tektronix!nosun!techbook!fzsitvayReferences:
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!zephyr.ens.tek.com!tektronix!nosun!techbook!fzsitvay From: fzsitvay@techbook.com (Frank Zsitvay) Newsgroups: comp.os.msdos.programmer,comp.sys.zenith,comp.sys.ibm.pc.misc Subject: Re: Programming the keyboard port Message-ID: <1990Aug18.105156.21058@techbook.com> Date: 18 Aug 90 10:51:56 GMT References: <90226.104110TOMIII@MTUS5.BITNET> Organization: TECHbooks of Beaverton Oregon - Public Access Unix Lines: 31