Path: utzoo!attcan!uunet!know!zaphod.mps.ohio-state.edu!mips!daver!bungi.com!news
From: kls@halas.UUCP (Karl Swartz)
Newsgroups: comp.sys.nsc.32k
Subject: /dev/rtc (and /dev/rom)
Message-ID: <199009140215.AA00063@halas.UUCP>
Date: 14 Sep 90 10:15:22 GMT
Sender: news@daver.bungi.com
Lines: 33
Approved: news@daver.bungi.com

I just installed Johan's /dev/rtc code and it works just fine.
A couple of missing pieces did crop up along the way though:

    /usr/src/minix/Makefile

	Add -DRTC to CFLAGS to enable RTC code.

    /usr/src/minix/h/com.h

	Minor device numbers for the new devices need to be
	added after the define for NULL_DEV:

	    #define NULL_DEV	3
	    #define RTC_DEV	4
	    #define ROM_DEV	5

I also discovered in the process of seeing if the code worked
that the -x option to od does not work properly.  Rather than
displaying each word in hex, it displays the lower word of each
*double* word in hex.  Sounds like the pointer is declared to
be an (int *) when it should be a (short *).  And when you use
od -o, don't forget that the RTC values are BCD.  That got me
confused for a minute or two.

Anyway, I plan on modifying the date command to read and write
/dev/rtc if it's found, and to do what makes sense at boot time.
(BTW, it appears that the system is on PST -- Pacific Standard
Time -- and not PDT.  Probably doesn't understand other zones
but I haven't looked at this one yet.)

Thanks for writing /dev/rtc and /dev/rom, Johan!

 -- Karl